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re PR tree-optimization/79159 (spurious array-bounds warning)

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PR tree-optimization/79159
	* tree-ssa-loop-niter.c (get_cst_init_from_scev): New function.
	(record_nonwrapping_iv): Imporve boundary using above function if no
	value range information.

	gcc/testsuite
	PR tree-optimization/79159
	* g++.dg/tree-ssa/pr79159.C: New test.

From-SVN: r244868
This commit is contained in:
Bin Cheng 2017-01-24 13:09:27 +00:00 committed by Bin Cheng
parent 5fd1486ce5
commit cf8d19de26
4 changed files with 71 additions and 2 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2017-01-24 Bin Cheng <bin.cheng@arm.com>
PR tree-optimization/79159
* tree-ssa-loop-niter.c (get_cst_init_from_scev): New function.
(record_nonwrapping_iv): Imporve boundary using above function if no
value range information.
2017-01-24 Pekka Jääskeläinen <pekka@parmance.com>
Martin Jambor <mjambor@suse.cz>

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2017-01-24 Bin Cheng <bin.cheng@arm.com>
PR tree-optimization/79159
* g++.dg/tree-ssa/pr79159.C: New test.
2017-01-24 Pekka Jääskeläinen <pekka@parmance.com>
Martin Jambor <mjambor@suse.cz>

18
gcc/testsuite/g++.dg/tree-ssa/pr79159.C Normal file
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@ -0,0 +1,18 @@
/* { dg-do compile } */
/* { dg-options "-O3 -Wall" } */
void foo(float tmpCorr[9][9]);
float bar;
void finalDigits(int& n)
{
float tmpCorr[9][9] = {{0}};
foo(tmpCorr);
for (int i = 0; i < n; i++) {
for (int j = i+1; j < n; j++) {
bar = tmpCorr[i][j];
}
}
}

43
gcc/tree-ssa-loop-niter.c
View File

@ -3059,6 +3059,43 @@ record_control_iv (struct loop *loop, struct tree_niter_desc *niter)
return;
}
/* This function returns TRUE if below conditions are satisfied:
1) VAR is SSA variable.
2) VAR is an IV:{base, step} in its defining loop.
3) IV doesn't overflow.
4) Both base and step are integer constants.
5) Base is the MIN/MAX value depends on IS_MIN.
Store value of base to INIT correspondingly. */
static bool
get_cst_init_from_scev (tree var, wide_int *init, bool is_min)
{
if (TREE_CODE (var) != SSA_NAME)
return false;
gimple *def_stmt = SSA_NAME_DEF_STMT (var);
struct loop *loop = loop_containing_stmt (def_stmt);
if (loop == NULL)
return false;
affine_iv iv;
if (!simple_iv (loop, loop, var, &iv, false))
return false;
if (!iv.no_overflow)
return false;
if (TREE_CODE (iv.base) != INTEGER_CST || TREE_CODE (iv.step) != INTEGER_CST)
return false;
if (is_min == tree_int_cst_sign_bit (iv.step))
return false;
*init = iv.base;
return true;
}
/* Record the estimate on number of iterations of LOOP based on the fact that
the induction variable BASE + STEP * i evaluated in STMT does not wrap and
its values belong to the range <LOW, HIGH>. REALISTIC is true if the
@ -3100,7 +3137,8 @@ record_nonwrapping_iv (struct loop *loop, tree base, tree step, gimple *stmt,
if (TREE_CODE (orig_base) == SSA_NAME
&& TREE_CODE (high) == INTEGER_CST
&& INTEGRAL_TYPE_P (TREE_TYPE (orig_base))
&& get_range_info (orig_base, &min, &max) == VR_RANGE
&& (get_range_info (orig_base, &min, &max) == VR_RANGE
|| get_cst_init_from_scev (orig_base, &max, false))
&& wi::gts_p (high, max))
base = wide_int_to_tree (unsigned_type, max);
else if (TREE_CODE (base) != INTEGER_CST
@ -3117,7 +3155,8 @@ record_nonwrapping_iv (struct loop *loop, tree base, tree step, gimple *stmt,
if (TREE_CODE (orig_base) == SSA_NAME
&& TREE_CODE (low) == INTEGER_CST
&& INTEGRAL_TYPE_P (TREE_TYPE (orig_base))
&& get_range_info (orig_base, &min, &max) == VR_RANGE
&& (get_range_info (orig_base, &min, &max) == VR_RANGE
|| get_cst_init_from_scev (orig_base, &min, true))
&& wi::gts_p (min, low))
base = wide_int_to_tree (unsigned_type, min);
else if (TREE_CODE (base) != INTEGER_CST