[PATCH] PHIOPT: Improve minmax diamond detection for phiopt1

[PATCH] PHIOPT: Improve minmax diamond detection for phiopt1

[Andrew Pinski]

For diamond bb phi node detection, there is a check
to make sure bb1 is not empty. But in the case where
bb1 is empty except for a predicate, empty_block_p
will still return true but the minmax code handles
that case already so there is no reason to check
if the basic block is empty.

This patch removes that check and removes some
xfails.

OK? Bootstrapped and tested on x86_64-linux-gnu.

gcc/ChangeLog:

	* tree-ssa-phiopt.cc (tree_ssa_phiopt_worker):
	Remove check on empty_block_p.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/phi-opt-5.c: Remvoe some xfail.
---
 gcc/testsuite/gcc.dg/tree-ssa/phi-opt-5.c | 10 +++++-----
 gcc/tree-ssa-phiopt.cc                    |  3 +--
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-5.c b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-5.c
index 5a00f3ddf8c..5f78a1ba6dc 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-5.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-5.c
@@ -16,9 +16,9 @@ float repl1 (float varx)
    varx_4 = MIN_EXPR <1.0e+0, varx_2>;
    varx_5 = MAX_EXPR <varx_4, 0.0>;  */  
 
-/* phiopt1 confused by predictors.  */
-/* { dg-final { scan-tree-dump "varx.*MIN_EXPR.*1\\.0" "phiopt1" { xfail *-*-* } } } */
-/* { dg-final { scan-tree-dump "varx.*MAX_EXPR.*0\\.0" "phiopt1" { xfail *-*-* } } } */
+/* phiopt1 was confused by predictors.  */
+/* { dg-final { scan-tree-dump "varx.*MIN_EXPR.*1\\.0" "phiopt1" } } */
+/* { dg-final { scan-tree-dump "varx.*MAX_EXPR.*0\\.0" "phiopt1" } } */
 /* { dg-final { scan-tree-dump "varx.*MIN_EXPR.*1\\.0" "phiopt2"} } */
 /* { dg-final { scan-tree-dump "varx.*MAX_EXPR.*0\\.0" "phiopt2"} } */
 
@@ -38,7 +38,7 @@ float repl2 (float vary)
    vary_5 = MIN_EXPR <vary_4, 1.0e+0>;  */
 
 /* phiopt1 confused by predictors.  */
-/* { dg-final { scan-tree-dump "vary.*MAX_EXPR.*0\\.0" "phiopt1" { xfail *-*-* } } } */
+/* { dg-final { scan-tree-dump "vary.*MAX_EXPR.*0\\.0" "phiopt1" } } */
 /* { dg-final { scan-tree-dump "vary.*MIN_EXPR.*1\\.0" "phiopt1" { xfail *-*-* } } } */
 /* { dg-final { scan-tree-dump "vary.*MAX_EXPR.*0\\.0" "phiopt2"} } */
 /* { dg-final { scan-tree-dump "vary.*MIN_EXPR.*1\\.0" "phiopt2"} } */
@@ -61,6 +61,6 @@ float repl3 (float varz, float vara, float varb)
   vara_6 = MAX_EXPR <varb_5, varz_2>;  */
 
 /* phiopt1 confused by predictors.  */
-/* { dg-final { scan-tree-dump "vara.*MAX_EXPR" "phiopt1" { xfail *-*-* } } } */
+/* { dg-final { scan-tree-dump "vara.*MAX_EXPR" "phiopt1" } } */
 /* { dg-final { scan-tree-dump "if .*varz" "phiopt2"} } */
 /* { dg-final { scan-tree-dump "vara.*MAX_EXPR" "phiopt2"} } */
diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index 945507be11e..8c5c8d8c250 100644
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -209,8 +209,7 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads, bool early_p)
 	    hoist_adjacent_loads (bb, bb1, bb2, bb3);
 	  continue;
 	}
-      else if (EDGE_SUCC (bb1, 0)->dest == EDGE_SUCC (bb2, 0)->dest
-	       && !empty_block_p (bb1))
+      else if (EDGE_SUCC (bb1, 0)->dest == EDGE_SUCC (bb2, 0)->dest)
 	{
 	  diamond_p = true;
 	  e2 = EDGE_SUCC (bb2, 0);
-- 
2.31.1

Re: [PATCH] PHIOPT: Improve minmax diamond detection for phiopt1

[Jeff Law]

On 4/19/23 15:36, Andrew Pinski via Gcc-patches wrote:
> For diamond bb phi node detection, there is a check
> to make sure bb1 is not empty. But in the case where
> bb1 is empty except for a predicate, empty_block_p
> will still return true but the minmax code handles
> that case already so there is no reason to check
> if the basic block is empty.
> 
> This patch removes that check and removes some
> xfails.
> 
> OK? Bootstrapped and tested on x86_64-linux-gnu.
> 
> gcc/ChangeLog:
> 
> 	* tree-ssa-phiopt.cc (tree_ssa_phiopt_worker):
> 	Remove check on empty_block_p.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* gcc.dg/tree-ssa/phi-opt-5.c: Remvoe some xfail.
OK
jeff