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tree-optimization/98513 - fix bug in range intersection code

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This fixes a premature optimization in the range intersection code
which assumes earlier branches have to be taken, not taking into
account that for symbolic ranges we cannot always compare endpoints.
The fix is to instantiate the compare deemed redundant (which then
fails as undecidable for the testcase).

2021-01-06  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/98513
	* value-range.cc (intersect_ranges): Compare the upper bounds
	for the expected relation.

	* gcc.dg/tree-ssa/pr98513.c: New testcase.
This commit is contained in:
Richard Biener 2021-01-06 09:26:55 +01:00
parent 57706dd7e0
commit a05cc70a6c
2 changed files with 51 additions and 2 deletions
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47
gcc/testsuite/gcc.dg/tree-ssa/pr98513.c Normal file
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@ -0,0 +1,47 @@
/* { dg-do run } */
/* { dg-options "-O2 -fgimple" } */
__attribute__((noipa))
void __GIMPLE (ssa,startwith("evrp"))
foo (int x, int minus_1)
{
int tem;
unsigned int _1;
unsigned int _2;
__BB(2):
tem_4 = minus_1_3(D);
tem_5 = tem_4 + 2;
_1 = (unsigned int) x_6(D);
_2 = _1 + 2147483647u;
if (_2 > 1u)
goto __BB3;
else
goto __BB6;
__BB(3):
if (x_6(D) <= tem_5)
goto __BB4;
else
goto __BB6;
__BB(4):
if (x_6(D) > 5)
goto __BB5;
else
goto __BB6;
__BB(5):
__builtin_exit (0);
__BB(6):
return;
}
int
main()
{
foo (10, 100);
__builtin_abort ();
}

6
gcc/value-range.cc
View File

@ -974,7 +974,8 @@ intersect_ranges (enum value_range_kind *vr0type,
}
else if ((operand_less_p (vr1min, *vr0max) == 1
|| operand_equal_p (vr1min, *vr0max, 0))
&& operand_less_p (*vr0min, vr1min) == 1)
&& operand_less_p (*vr0min, vr1min) == 1
&& operand_less_p (*vr0max, vr1max) == 1)
{
/* [ ( ] ) or [ ]( ) */
if (*vr0type == VR_ANTI_RANGE
@ -1008,7 +1009,8 @@ intersect_ranges (enum value_range_kind *vr0type,
}
else if ((operand_less_p (*vr0min, vr1max) == 1
|| operand_equal_p (*vr0min, vr1max, 0))
&& operand_less_p (vr1min, *vr0min) == 1)
&& operand_less_p (vr1min, *vr0min) == 1
&& operand_less_p (vr1max, *vr0max) == 1)
{
/* ( [ ) ] or ( )[ ] */
if (*vr0type == VR_ANTI_RANGE