re PR rtl-optimization/19210 (not using do-loop for some loops)
gcc:
2005-07-21 Paolo Bonzini <bonzini@gnu.org>
Zdenek Dvorak <dvorakz@suse.cz>
PR tree-optimization/19210
* common.opt (Wunsafe-loop-optimizations, funsafe-loop-optimizations):
New.
* Makefile.in (tree-ssa-loop-niter.o): Depend intl.o.
* loop-iv.c (get_simple_loop_desc): If -funsafe-loop-optimizations,
rely on unproven assumptions.
* predict.c (predict_loops): Adjust call to number_of_iterations_exit.
* tree-flow.h (number_of_iterations_exit): Add final parameter.
* tree-scalar-evolution.c (number_of_iterations_in_loop): Adjust call
to number_of_iterations_exit.
* tree-ssa-loop-ivcanon.c (empty_loop_p): Likewise.
* tree-ssa-loop-ivopts.c (niter_for_exit): Likewise.
* tree-ssa-loop-niter.c (find_loop_niter,
estimate_numbers_of_iterations_loop): Likewise.
(number_of_iterations_exit): Honor the new options.
* doc/invoke.texi (Wunsafe-loop-optimizations,
funsafe-loop-optimizations): Document them.
gcc/testsuite:
2005-07-21 Paolo Bonzini <bonzini@gnu.org>
* gcc.dg/tree-ssa/pr19210-1.c: New.
* gcc.dg/tree-ssa/pr19210-2.c: New.
Co-Authored-By: Zdenek Dvorak <dvorakz@suse.cz>
From-SVN: r102225
This commit is contained in:
Paolo Bonzini
Paolo Bonzini
parent
cb83c2ec41
commit
f9cc1a70d5
@ -1,3 +1,24 @@
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2005-07-21 Paolo Bonzini <bonzini@gnu.org>
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Zdenek Dvorak <dvorakz@suse.cz>
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PR tree-optimization/19210
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* common.opt (Wunsafe-loop-optimizations, funsafe-loop-optimizations):
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New.
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* Makefile.in (tree-ssa-loop-niter.o): Depend intl.o.
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* loop-iv.c (get_simple_loop_desc): If -funsafe-loop-optimizations,
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rely on unproven assumptions.
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* predict.c (predict_loops): Adjust call to number_of_iterations_exit.
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* tree-flow.h (number_of_iterations_exit): Add final parameter.
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* tree-scalar-evolution.c (number_of_iterations_in_loop): Adjust call
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to number_of_iterations_exit.
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* tree-ssa-loop-ivcanon.c (empty_loop_p): Likewise.
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* tree-ssa-loop-ivopts.c (niter_for_exit): Likewise.
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* tree-ssa-loop-niter.c (find_loop_niter,
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estimate_numbers_of_iterations_loop): Likewise.
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(number_of_iterations_exit): Honor the new options.
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* doc/invoke.texi (Wunsafe-loop-optimizations,
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funsafe-loop-optimizations): Document them.
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2005-07-21 Richard Sandiford <richard@codesourcery.com>
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PR rtl-optimization/22167
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@ -1869,7 +1869,7 @@ tree-ssa-loop-niter.o : tree-ssa-loop-niter.c $(TREE_FLOW_H) $(CONFIG_H) \
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$(SYSTEM_H) $(RTL_H) $(TREE_H) $(TM_P_H) $(CFGLOOP_H) $(PARAMS_H) \
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tree-inline.h output.h $(DIAGNOSTIC_H) $(TM_H) coretypes.h $(TREE_DUMP_H) \
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$(FLAGS_H) tree-pass.h $(SCEV_H) $(TREE_DATA_REF_H) $(BASIC_BLOCK_H) \
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$(GGC_H) hard-reg-set.h tree-chrec.h
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$(GGC_H) hard-reg-set.h tree-chrec.h intl.h
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tree-ssa-loop-ivcanon.o : tree-ssa-loop-ivcanon.c $(TREE_FLOW_H) $(CONFIG_H) \
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$(SYSTEM_H) $(RTL_H) $(TREE_H) $(TM_P_H) $(CFGLOOP_H) $(PARAMS_H) \
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tree-inline.h output.h $(DIAGNOSTIC_H) $(TM_H) coretypes.h $(TREE_DUMP_H) \
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@ -2288,7 +2288,7 @@ cfgloopanal.o : cfgloopanal.c $(CONFIG_H) $(SYSTEM_H) $(RTL_H) \
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$(OBSTACK_H) output.h
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loop-iv.o : loop-iv.c $(CONFIG_H) $(SYSTEM_H) $(RTL_H) $(BASIC_BLOCK_H) \
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hard-reg-set.h $(CFGLOOP_H) $(EXPR_H) coretypes.h $(TM_H) $(OBSTACK_H) \
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output.h
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output.h intl.h
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loop-invariant.o : loop-invariant.c $(CONFIG_H) $(SYSTEM_H) $(RTL_H) \
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$(BASIC_BLOCK_H) hard-reg-set.h $(CFGLOOP_H) $(EXPR_H) coretypes.h \
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$(TM_H) function.h $(FLAGS_H) $(DF_H) $(OBSTACK_H) output.h
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@ -93,6 +93,10 @@ Wlarger-than-
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Common RejectNegative Joined UInteger
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-Wlarger-than-<number> Warn if an object is larger than <number> bytes
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Wunsafe-loop-optimizations
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Common Var(warn_unsafe_loop_optimizations)
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Warn if the loop cannot be optimized due to nontrivial assumptions.
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Wmissing-noreturn
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Common Var(warn_missing_noreturn)
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Warn about functions which might be candidates for __attribute__((noreturn))
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@ -402,6 +406,10 @@ fforce-mem
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Common Report Var(flag_force_mem)
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Copy memory operands into registers before use
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fforward-propagate
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Common Report Var(flag_forward_propagate)
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Perform a forward propagation pass on RTL
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; Nonzero means don't put addresses of constant functions in registers.
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; Used for compiling the Unix kernel, where strange substitutions are
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; done on the assembly output.
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@ -963,6 +971,13 @@ funroll-all-loops
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Common Report Var(flag_unroll_all_loops)
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Perform loop unrolling for all loops
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; Nonzero means that loop optimizer may assume that the induction variables
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; that control loops do not overflow and that the loops with nontrivial
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; exit condition are not infinite
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funsafe-loop-optimizations
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Common Report Var(flag_unsafe_loop_optimizations)
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Allow loop optimizations to assume that the loops behave in normal way
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; Nonzero means that unsafe floating-point math optimizations are allowed
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; for the sake of speed. IEEE compliance is not guaranteed, and operations
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; are allowed to assume that their arguments and results are "normal"
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@ -230,7 +230,7 @@ Objective-C and Objective-C++ Dialects}.
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-Wimport -Wno-import -Winit-self -Winline @gol
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-Wno-int-to-pointer-cast @gol
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-Wno-invalid-offsetof -Winvalid-pch @gol
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-Wlarger-than-@var{len} -Wlong-long @gol
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-Wlarger-than-@var{len} -Wunsafe-loop-optimizations -Wlong-long @gol
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-Wmain -Wmissing-braces -Wmissing-field-initializers @gol
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-Wmissing-format-attribute -Wmissing-include-dirs @gol
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-Wmissing-noreturn @gol
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@ -311,7 +311,7 @@ Objective-C and Objective-C++ Dialects}.
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-fno-default-inline -fno-defer-pop -floop-optimize2 -fmove-loop-invariants @gol
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-fno-function-cse -fno-guess-branch-probability @gol
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-fno-inline -fno-math-errno -fno-peephole -fno-peephole2 @gol
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-funsafe-math-optimizations -ffinite-math-only @gol
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-funsafe-math-optimizations -funsafe-loop-optimizations -ffinite-math-only @gol
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-fno-trapping-math -fno-zero-initialized-in-bss @gol
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-fomit-frame-pointer -foptimize-register-move @gol
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-foptimize-sibling-calls -fprefetch-loop-arrays @gol
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@ -2988,6 +2988,13 @@ global variable or whenever a built-in function is shadowed.
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@opindex Wlarger-than
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Warn whenever an object of larger than @var{len} bytes is defined.
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@item -Wunsafe-loop-optimizations
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@opindex Wunsafe-loop-optimizations
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Warn if the loop cannot be optimized because the compiler could not
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assume anything on the bounds of the loop indices. With
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@option{-funsafe-loop-optimizations} warn if the compiler made
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such assumptions.
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@item -Wpointer-arith
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@opindex Wpointer-arith
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Warn about anything that depends on the ``size of'' a function type or
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@ -4728,6 +4735,15 @@ Perform loop optimizations using the new loop optimizer. The optimizations
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(loop unrolling, peeling and unswitching, loop invariant motion) are enabled
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by separate flags.
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@item -funsafe-loop-optimizations
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@opindex funsafe-loop-optimizations
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If given, the loop optimizer will assume that loop indices do not
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overflow, and that the loops with nontrivial exit condition are not
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infinite. This enables a wider range of loop optimizations even if
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the loop optimizer itself cannot prove that these assumptions are valid.
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Using @option{-Wunsafe-loop-optimizations}, the compiler will warn you
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if it finds this kind of loop.
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@item -fcrossjumping
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@opindex crossjumping
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Perform cross-jumping transformation. This transformation unifies equivalent code and save code size. The
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@ -57,7 +57,9 @@ Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
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#include "basic-block.h"
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#include "cfgloop.h"
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#include "expr.h"
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#include "intl.h"
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#include "output.h"
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#include "toplev.h"
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/* The insn information. */
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@ -2692,6 +2694,41 @@ get_simple_loop_desc (struct loop *loop)
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find_simple_exit (loop, desc);
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loop->aux = desc;
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if (desc->simple_p && (desc->assumptions || desc->infinite))
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{
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const char *wording;
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/* Assume that no overflow happens and that the loop is finite.
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We already warned at the tree level if we ran optimizations there. */
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if (!flag_tree_loop_optimize && warn_unsafe_loop_optimizations)
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{
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if (desc->infinite)
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{
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wording =
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flag_unsafe_loop_optimizations
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? N_("assuming that the loop is not infinite")
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: N_("cannot optimize possibly infinite loops");
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warning (OPT_Wunsafe_loop_optimizations, "%s",
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gettext (wording));
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}
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if (desc->assumptions)
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{
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wording =
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flag_unsafe_loop_optimizations
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? N_("assuming that the loop counter does not overflow")
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: N_("cannot optimize loop, the loop counter may overflow");
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warning (OPT_Wunsafe_loop_optimizations, "%s",
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gettext (wording));
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}
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}
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if (flag_unsafe_loop_optimizations)
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{
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desc->assumptions = NULL_RTX;
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desc->infinite = NULL_RTX;
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}
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}
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return desc;
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}
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@ -643,7 +643,7 @@ predict_loops (struct loops *loops_info, bool rtlsimpleloops)
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{
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tree niter = NULL;
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if (number_of_iterations_exit (loop, exits[j], &niter_desc))
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if (number_of_iterations_exit (loop, exits[j], &niter_desc, false))
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niter = niter_desc.niter;
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if (!niter || TREE_CODE (niter_desc.niter) != INTEGER_CST)
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niter = loop_niter_by_eval (loop, exits[j]);
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@ -1,3 +1,8 @@
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2005-07-21 Paolo Bonzini <bonzini@gnu.org>
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* gcc.dg/tree-ssa/pr19210-1.c: New.
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* gcc.dg/tree-ssa/pr19210-2.c: New.
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2005-07-21 Richard Sandiford <richard@codesourcery.com>
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PR rtl-optimization/22167
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20
gcc/testsuite/gcc.dg/tree-ssa/pr19210-1.c
Normal file
20
gcc/testsuite/gcc.dg/tree-ssa/pr19210-1.c
Normal file
@ -0,0 +1,20 @@
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/* { dg-do compile } */
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/* { dg-options "-O2 -Wunsafe-loop-optimizations" } */
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extern void g(void);
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void
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f (unsigned n)
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{
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unsigned k;
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for(k = 0;k <= n;k++) /* { dg-warning "cannot optimize.*infinite loops" } */
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g();
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for(k = 0;k <= n;k += 4) /* { dg-warning "cannot optimize.*overflow" } */
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g();
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for(k = 5;k <= n;k += 5) /* { dg-warning "cannot optimize.*overflow" } */
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g();
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for(k = 15;k >= n;k--) /* { dg-warning "cannot optimize.*infinite" } */
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g();
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}
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21
gcc/testsuite/gcc.dg/tree-ssa/pr19210-2.c
Normal file
21
gcc/testsuite/gcc.dg/tree-ssa/pr19210-2.c
Normal file
@ -0,0 +1,21 @@
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/* { dg-do compile } */
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/* { dg-options "-O2 -funsafe-loop-optimizations -Wunsafe-loop-optimizations" } */
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extern void g(void);
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void
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f (unsigned n)
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{
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unsigned k;
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for(k = 0;k <= n;k++) /* { dg-warning "assuming.*not infinite" } */
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g();
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for(k = 5;k <= n;k += 4) /* { dg-warning "assuming.*not overflow" } */
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g();
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for(k = 5;k <= n;k += 5) /* { dg-warning "assuming.*not overflow" } */
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g();
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for(k = 15;k >= n;k--) /* { dg-warning "assuming.*not infinite" } */
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g();
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}
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@ -722,7 +722,7 @@ void remove_empty_loops (struct loops *);
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void tree_ssa_iv_optimize (struct loops *);
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bool number_of_iterations_exit (struct loop *, edge,
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struct tree_niter_desc *niter);
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struct tree_niter_desc *niter, bool);
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tree find_loop_niter (struct loop *, edge *);
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tree loop_niter_by_eval (struct loop *, edge);
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tree find_loop_niter_by_eval (struct loop *, edge *);
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@ -2235,7 +2235,7 @@ number_of_iterations_in_loop (struct loop *loop)
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if (!exit)
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goto end;
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if (!number_of_iterations_exit (loop, exit, &niter_desc))
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if (!number_of_iterations_exit (loop, exit, &niter_desc, false))
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goto end;
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type = TREE_TYPE (niter_desc.niter);
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@ -393,7 +393,7 @@ empty_loop_p (struct loop *loop)
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return false;
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/* The loop must be finite. */
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if (!number_of_iterations_exit (loop, exit, &niter))
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if (!number_of_iterations_exit (loop, exit, &niter, false))
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return false;
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/* Values of all loop exit phi nodes must be invariants. */
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@ -712,7 +712,8 @@ niter_for_exit (struct ivopts_data *data, edge exit)
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nfe_desc = xmalloc (sizeof (struct nfe_cache_elt));
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nfe_desc->exit = exit;
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nfe_desc->valid_p = number_of_iterations_exit (data->current_loop,
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exit, &nfe_desc->niter);
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exit, &nfe_desc->niter,
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true);
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*slot = nfe_desc;
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}
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else
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@ -29,6 +29,7 @@ Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
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#include "basic-block.h"
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#include "output.h"
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#include "diagnostic.h"
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#include "intl.h"
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#include "tree-flow.h"
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#include "tree-dump.h"
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#include "cfgloop.h"
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@ -39,6 +40,7 @@ Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
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#include "tree-data-ref.h"
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#include "params.h"
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#include "flags.h"
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#include "toplev.h"
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#include "tree-inline.h"
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#define SWAP(X, Y) do { void *tmp = (X); (X) = (Y); (Y) = tmp; } while (0)
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@ -906,11 +908,14 @@ simplify_using_outer_evolutions (struct loop *loop, tree expr)
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EXIT (an exit edge of the LOOP) in NITER. Returns true if some
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useful information could be derived (and fields of NITER has
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meaning described in comments at struct tree_niter_desc
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declaration), false otherwise. */
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declaration), false otherwise. If WARN is true and
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-Wunsafe-loop-optimizations was given, warn if the optimizer is going to use
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potentially unsafe assumptions. */
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bool
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number_of_iterations_exit (struct loop *loop, edge exit,
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struct tree_niter_desc *niter)
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struct tree_niter_desc *niter,
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bool warn)
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{
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tree stmt, cond, type;
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tree op0, base0, step0;
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@ -990,7 +995,45 @@ number_of_iterations_exit (struct loop *loop, edge exit,
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= simplify_using_initial_conditions (loop,
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niter->may_be_zero,
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&niter->additional_info);
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return integer_onep (niter->assumptions);
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if (integer_onep (niter->assumptions))
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return true;
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/* With -funsafe-loop-optimizations we assume that nothing bad can happen.
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But if we can prove that there is overflow or some other source of weird
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behavior, ignore the loop even with -funsafe-loop-optimizations. */
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if (integer_zerop (niter->assumptions))
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return false;
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if (flag_unsafe_loop_optimizations)
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niter->assumptions = boolean_true_node;
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if (warn)
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{
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const char *wording;
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location_t loc = EXPR_LOCATION (stmt);
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/* We can provide a more specific warning if one of the operator is
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constant and the other advances by +1 or -1. */
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if (step1 ? !step0 && (integer_onep (step1) || integer_all_onesp (step1))
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: step0 && (integer_onep (step0) || integer_all_onesp (step0)))
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wording =
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flag_unsafe_loop_optimizations
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? N_("assuming that the loop is not infinite")
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: N_("cannot optimize possibly infinite loops");
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else
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wording =
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flag_unsafe_loop_optimizations
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? N_("assuming that the loop counter does not overflow")
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: N_("cannot optimize loop, the loop counter may overflow");
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if (LOCATION_LINE (loc) > 0)
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warning (OPT_Wunsafe_loop_optimizations, "%H%s", &loc, gettext (wording));
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else
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warning (OPT_Wunsafe_loop_optimizations, "%s", gettext (wording));
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}
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return flag_unsafe_loop_optimizations;
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}
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/* Try to determine the number of iterations of LOOP. If we succeed,
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@ -1014,7 +1057,7 @@ find_loop_niter (struct loop *loop, edge *exit)
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if (!just_once_each_iteration_p (loop, ex->src))
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continue;
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if (!number_of_iterations_exit (loop, ex, &desc))
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if (!number_of_iterations_exit (loop, ex, &desc, false))
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continue;
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if (nonzero_p (desc.may_be_zero))
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@ -1360,7 +1403,7 @@ estimate_numbers_of_iterations_loop (struct loop *loop)
|
||||
exits = get_loop_exit_edges (loop, &n_exits);
|
||||
for (i = 0; i < n_exits; i++)
|
||||
{
|
||||
if (!number_of_iterations_exit (loop, exits[i], &niter_desc))
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if (!number_of_iterations_exit (loop, exits[i], &niter_desc, false))
|
||||
continue;
|
||||
|
||||
niter = niter_desc.niter;
|
||||
|
||||
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