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tree-optimization/125545 - reassoc insering after asm goto

Message ID 20260602134527.739364BA2E29@sourceware.org
State Committed
Headers
Series tree-optimization/125545 - reassoc insering after asm goto |

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Commit Message

Richard Biener June 2, 2026, 1:44 p.m. UTC 
  There's one case we can handle just fine which is when the asm goto
has a single successor (it's fallthru edge, possibly shared with
an asm goto label).  As we're using dominance based insertion
point discovery we have to handle this case.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.

	PR tree-optimization/125545
	* tree-ssa-reassoc.cc (insert_stmt_after): Allow asm goto
	with a single successor.

	* gcc.dg/torture/pr125545.c: New testcase.
---
 gcc/testsuite/gcc.dg/torture/pr125545.c | 9 +++++++++
 gcc/tree-ssa-reassoc.cc                 | 3 ++-
 2 files changed, 11 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.dg/torture/pr125545.c
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Patch

diff --git a/gcc/testsuite/gcc.dg/torture/pr125545.c b/gcc/testsuite/gcc.dg/torture/pr125545.c
new file mode 100644
index 00000000000..084ce567851
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr125545.c
@@ -0,0 +1,9 @@ 
+/* { dg-do compile } */
+
+int b(int c)
+{
+  int a;
+  __asm__ goto("" : "=r"(a) : : : d);
+d:
+  return c && a != 42 && a >= 42;
+}
diff --git a/gcc/tree-ssa-reassoc.cc b/gcc/tree-ssa-reassoc.cc
index e97385611e9..4b47fb20f3a 100644
--- a/gcc/tree-ssa-reassoc.cc
+++ b/gcc/tree-ssa-reassoc.cc
@@ -1521,7 +1521,8 @@  insert_stmt_after (gimple *stmt, gimple *insert_point)
       return;
     }
   else if (gimple_code (insert_point) == GIMPLE_ASM
-	   && gimple_asm_nlabels (as_a <gasm *> (insert_point)) != 0)
+	   && gimple_asm_nlabels (as_a <gasm *> (insert_point)) != 0
+	   && !single_succ_p (gimple_bb (insert_point)))
     /* We have no idea where to insert - it depends on where the
        uses will be placed.  */
     gcc_unreachable ();