A DEBUG_INSN VAR_LOCATION can mention if_info->x without representing an
ordinary use. Exclude debug instructions from the overlap scan so that
debug-only payloads do not suppress min/max if-conversion.
PR rtl-optimization/127423
gcc/ChangeLog:
* ifcvt.cc (noce_get_alt_condition): Ignore debug instructions when
checking whether if_info->x is mentioned in the interval.
gcc/testsuite/ChangeLog:
* gcc.target/riscv/pr127423.c: New test.
Assisted-by: OpenAI Codex 5.6 Sol, co-reviewed by Claude and Yongqiang Tian.
Signed-off-by: Yongqiang Tian <[email protected]>
---
gcc/ifcvt.cc | 3 ++-
gcc/testsuite/gcc.target/riscv/pr127423.c | 17 +++++++++++++++++
2 files changed, 19 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.target/riscv/pr127423.c
diff --git a/gcc/ifcvt.cc b/gcc/ifcvt.cc
index 7d23ce115bd..618c2976c5d 100644
--- a/gcc/ifcvt.cc
+++ b/gcc/ifcvt.cc
@@ -3038,7 +3038,8 @@ noce_get_alt_condition (noce_if_info *if_info, rtx target,
/* X may not be mentioned in the range (cond_earliest, jump]. */
for (insn = if_info->jump; insn != *earliest; insn = PREV_INSN (insn))
- if (INSN_P (insn) && reg_overlap_mentioned_p (if_info->x, PATTERN (insn)))
+ if (NONDEBUG_INSN_P (insn)
+ && reg_overlap_mentioned_p (if_info->x, PATTERN (insn)))
return NULL;
/* A and B may not be modified in the range [cond_earliest, jump). */
diff --git a/gcc/testsuite/gcc.target/riscv/pr127423.c
b/gcc/testsuite/gcc.target/riscv/pr127423.c
new file mode 100644
index 00000000000..47caa270644
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/pr127423.c
@@ -0,0 +1,17 @@
+/* PR rtl-optimization/127423 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-tree-forwprop -fdisable-tree-phiopt1
-fdisable-tree-phiopt2 -fdisable-tree-phiopt3 -fdisable-tree-phiopt4
-march=rv64gc_zbb -mabi=lp64d -ffunction-sections -fcompare-debug" } */
+
+#define ATTR __attribute__ ((noinline, noclone))
+
+ATTR int
+debug_payload_min (int a, int b)
+{
+ _Bool pred = a < b;
+ asm volatile ("" : : "r" (pred));
+ int result = b;
+ int xghost = a;
+ if (pred)
+ result = a;
+ return result;
+}
--
2.34.1
