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re PR middle-end/61158 (negative shift at fold-const.c:12095) 

PR tree-optimization/61158
	* fold-const.c (fold_binary_loc): If X is zero-extended and
	shiftc >= prec, make sure zerobits is all ones instead of
	invoking undefined behavior.

	* gcc.dg/pr61158.c: New test.

From-SVN: r210467
This commit is contained in:
Jakub Jelinek 2014-05-15 12:01:11 +02:00
parent a2555c65a0
commit ceed6e6732
4 changed files with 37 additions and 7 deletions
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15
gcc/ChangeLog
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@ -1,12 +1,19 @@
2014-05-15 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/61158
* fold-const.c (fold_binary_loc): If X is zero-extended and
shiftc >= prec, make sure zerobits is all ones instead of
invoking undefined behavior.
2014-05-15 Zhenqiang Chen <zhenqiang.chen@linaro.org>
* regcprop.h: New file.
* regcprop.c (skip_debug_insn_p): New decl.
(replace_oldest_value_reg): Check skip_debug_insn_p.
(copyprop_hardreg_forward_bb_without_debug_insn.): New function.
* shrink-wrap.c: include regcprop.h
(prepare_shrink_wrap):
Call copyprop_hardreg_forward_bb_without_debug_insn.
(copyprop_hardreg_forward_bb_without_debug_insn): New function.
* shrink-wrap.c: Include regcprop.h.
(prepare_shrink_wrap): Call
copyprop_hardreg_forward_bb_without_debug_insn.
2014-05-15 Zhenqiang Chen <zhenqiang.chen@linaro.org>

12
gcc/fold-const.c
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@ -11972,11 +11972,17 @@ fold_binary_loc (location_t loc,
/* See if we can shorten the right shift. */
if (shiftc < prec)
shift_type = inner_type;
/* Otherwise X >> C1 is all zeros, so we'll optimize
it into (X, 0) later on by making sure zerobits
is all ones. */
}
}
zerobits = ~(unsigned HOST_WIDE_INT) 0;
zerobits >>= HOST_BITS_PER_WIDE_INT - shiftc;
zerobits <<= prec - shiftc;
if (shiftc < prec)
{
zerobits >>= HOST_BITS_PER_WIDE_INT - shiftc;
zerobits <<= prec - shiftc;
}
/* For arithmetic shift if sign bit could be set, zerobits
can contain actually sign bits, so no transformation is
possible, unless MASK masks them all away. In that
@ -11994,7 +12000,7 @@ fold_binary_loc (location_t loc,
/* ((X << 16) & 0xff00) is (X, 0). */
if ((mask & zerobits) == mask)
return omit_one_operand_loc (loc, type,
build_int_cst (type, 0), arg0);
build_int_cst (type, 0), arg0);
newmask = mask | zerobits;
if (newmask != mask && (newmask & (newmask + 1)) == 0)

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2014-05-15 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/61158
* gcc.dg/pr61158.c: New test.
2014-05-15 Andreas Schwab <schwab@suse.de>
* obj-c++.dg/exceptions-3.mm: Remove check for message no longer

12
gcc/testsuite/gcc.dg/pr61158.c Normal file
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@ -0,0 +1,12 @@
/* PR tree-optimization/61158 */
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-original" } */
unsigned long long
foo (unsigned int x)
{
return ((unsigned long long) x & 0x00ff000000000000ULL) >> 40;
}
/* { dg-final { scan-tree-dump "return 0;" "original" { target { ilp32 || lp64 } } } } */
/* { dg-final { cleanup-tree-dump "original" } } */