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phi-opt: Improve factor heurstic with constants and conversions from bool [PR116890]

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Take:
```
  if (t_3(D) != 0)
    goto <bb 3>;
  else
    goto <bb 4>;

  <bb 3>
  _8 = c_4(D) != 0;
  _9 = (int) _8;

  <bb 4>
  # e_2 = PHI <_9(3), 0(2)>
```

We should factor out the conversion here as that will allow a simplfication to
`(t_3 != 0) & (c_4 != 0)`. Unlike most other types; `a ? b : CST` will simplify
for boolean result type to either `a | b` or `a & b` so allowing this conversion
for all operations will be always profitable.

Bootstrapped and tested on x86_64-linux-gnu with no regressions.

Note on the phi-opt-7.c testcase change, we are now able to optimize this
and remove the if due to the factoring out now so this is an improvement.

	PR tree-optimization/116890

gcc/ChangeLog:

	* tree-ssa-phiopt.cc (factor_out_conditional_operation): Conversions
	from bool is also should be considered as wanting to happen.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/phi-opt-7.c: Update testcase for no ifs left.
	* gcc.dg/tree-ssa/phi-opt-42.c: New test.
	* gcc.dg/tree-ssa/phi-opt-43.c: New test.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
This commit is contained in:
Andrew Pinski 2024-09-30 16:44:44 +00:00
parent 8273e31adf
commit 698e0ec89b
4 changed files with 50 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

19
gcc/testsuite/gcc.dg/tree-ssa/phi-opt-42.c Normal file
View file

@ -0,0 +1,19 @@
/* { dg-do compile } */
/* { dg-options "-O1 -fdump-tree-optimized" } */
/* PR tree-optimization/116890 */
int f(int a, int b, int c)
{
int x;
if (c) x = a == 0;
else x = 0;
return x;
}
/* The if should have been removed as the the conversion from bool to int should have been factored out. */
/* { dg-final { scan-tree-dump-not "if" "optimized" } }*/
/* { dg-final { scan-tree-dump-times "\[^\r\n\]*_\[0-9\]* = a_\[0-9\]*.D. == 0" 1 "optimized" } } */
/* { dg-final { scan-tree-dump-times "\[^\r\n\]*_\[0-9\]* = c_\[0-9\]*.D. != 0" 1 "optimized" } } */

19
gcc/testsuite/gcc.dg/tree-ssa/phi-opt-43.c Normal file
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@ -0,0 +1,19 @@
/* { dg-do compile } */
/* { dg-options "-O1 -fdump-tree-optimized" } */
/* PR tree-optimization/116890 */
int f(_Bool a, _Bool b, int c)
{
int x;
if (c) x = a & b;
else x = 0;
return x;
}
/* The if should have been removed as the the conversion from bool to int should have been factored out. */
/* { dg-final { scan-tree-dump-not "if" "optimized" } }*/
/* { dg-final { scan-tree-dump-times "\[^\r\n\]*_\[0-9\]* = a_\[0-9\]*.D. & b_\[0-9\]*.D." 1 "optimized" } } */
/* { dg-final { scan-tree-dump-times "\[^\r\n\]*_\[0-9\]* = c_\[0-9\]*.D. != 0" 1 "optimized" } } */

6
gcc/testsuite/gcc.dg/tree-ssa/phi-opt-7.c
View file

@ -15,8 +15,8 @@ int f(int t, int c)
return g(d,e);
}
/* There should be one ifs as one of them should be changed into
a conditional and the other should be there still. */
/* { dg-final { scan-tree-dump-times "if" 1 "optimized" } }*/
/* There should be no ifs as this is converted into `(t != 0) & (c != 0)`.
/* { dg-final { scan-tree-dump-not "if" "optimized" } }*/
/* { dg-final { scan-tree-dump-times "\[^\r\n\]*_\[0-9\]* = c_\[0-9\]*.D. != 0" 1 "optimized" } } */
/* { dg-final { scan-tree-dump-times "\[^\r\n\]*_\[0-9\]* = t_\[0-9\]*.D. != 0" 1 "optimized" } } */

10
gcc/tree-ssa-phiopt.cc
View file

@ -345,9 +345,17 @@ factor_out_conditional_operation (edge e0, edge e1, gphi *phi,
if (gassign *assign = dyn_cast <gassign *> (stmt))
{
tree lhs = gimple_assign_lhs (assign);
tree lhst = TREE_TYPE (lhs);
enum tree_code ass_code
= gimple_assign_rhs_code (assign);
if (ass_code != MAX_EXPR && ass_code != MIN_EXPR)
if (ass_code != MAX_EXPR && ass_code != MIN_EXPR
/* Conversions from boolean like types is ok
as `a?1:b` and `a?0:b` will always simplify
to `a & b` or `a | b`.
See PR 116890. */
&& !(INTEGRAL_TYPE_P (lhst)
&& TYPE_UNSIGNED (lhst)
&& TYPE_PRECISION (lhst) == 1))
return NULL;
if (lhs != gimple_assign_rhs1 (arg0_def_stmt))
return NULL;