[gcc r12-7670] tree-optimization/102008 - restore if-conversion of adjacent loads

[gcc r12-7670] tree-optimization/102008 - restore if-conversion of adjacent loads

[Richard Biener]

https://gcc.gnu.org/g:f6fb661ea8ac7e17c6924719de6219f002c4efef

commit r12-7670-gf6fb661ea8ac7e17c6924719de6219f002c4efef
Author: Richard Biener <rguenther@suse.de>
Date:   Wed Mar 16 13:39:31 2022 +0100

    tree-optimization/102008 - restore if-conversion of adjacent loads
    
    The following re-orders the newly added code sinking pass before
    the last phiopt pass which performs hoisting of adjacent loads
    with the intent to enable if-conversion on those.
    
    I've added the aarch64 specific testcase from the PR.
    
    2022-03-16  Richard Biener  <rguenther@suse.de>
    
            PR tree-optimization/102008
            * passes.def: Move the added code sinking pass before the
            preceeding phiopt pass.
    
            * gcc.target/aarch64/pr102008.c: New testcase.

Diff:
---
 gcc/passes.def                              |  2 +-
 gcc/testsuite/gcc.target/aarch64/pr102008.c | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/gcc/passes.def b/gcc/passes.def
index f7718181038..c8903b4ec16 100644
--- a/gcc/passes.def
+++ b/gcc/passes.def
@@ -349,10 +349,10 @@ along with GCC; see the file COPYING3.  If not see
       /* After late CD DCE we rewrite no longer addressed locals into SSA
 	 form if possible.  */
       NEXT_PASS (pass_forwprop);
+      NEXT_PASS (pass_sink_code);
       NEXT_PASS (pass_phiopt, false /* early_p */);
       NEXT_PASS (pass_fold_builtins);
       NEXT_PASS (pass_optimize_widening_mul);
-      NEXT_PASS (pass_sink_code);
       NEXT_PASS (pass_store_merging);
       NEXT_PASS (pass_tail_calls);
       /* If DCE is not run before checking for uninitialized uses,
diff --git a/gcc/testsuite/gcc.target/aarch64/pr102008.c b/gcc/testsuite/gcc.target/aarch64/pr102008.c
new file mode 100644
index 00000000000..d54436c0ffd
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/pr102008.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+struct Foo {  int a;  int b; };
+
+int test(int side, const struct Foo *foo) {
+  if (side == 1) return foo->a;
+  return foo->b;
+}
+
+/* We want to if-convert the load, not the address.  */
+/* { dg-final { scan-assembler-not "add" } } */
+/* { dg-final { scan-assembler-times "csel" 1 } } */