[gcc r16-2450] aarch64: Fix fma steering when rename fails [PR120119]

[Andrew Pinski via Gcc-cvs]

https://gcc.gnu.org/g:66c879571ab1fbdb4b119b8b0a1a30ebc7160057

commit r16-2450-g66c879571ab1fbdb4b119b8b0a1a30ebc7160057
Author: Andrew Pinski <quic_apin...@quicinc.com>
Date:   Tue Jul 22 10:26:54 2025 -0700

    aarch64: Fix fma steering when rename fails [PR120119]
    
    Regrename can fail in some case and `insn_rr[INSN_UID (insn)].op_info`
    will be null. The FMA steering code was not expecting the failure to happen.
    This started to happen after early RA was added but it has been a latent bug
    before that.
    
    Build and tested for aarch64-linux-gnu.
    
            PR target/120119
    
    gcc/ChangeLog:
    
            * config/aarch64/cortex-a57-fma-steering.cc 
(func_fma_steering::analyze):
            Skip if renaming fails.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/torture/pr120119-1.C: New test.
    
    Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>

Diff:
---
 gcc/config/aarch64/cortex-a57-fma-steering.cc |  5 +++++
 gcc/testsuite/g++.dg/torture/pr120119-1.C     | 15 +++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/gcc/config/aarch64/cortex-a57-fma-steering.cc 
b/gcc/config/aarch64/cortex-a57-fma-steering.cc
index fd6da66d855e..f7675bed13d9 100644
--- a/gcc/config/aarch64/cortex-a57-fma-steering.cc
+++ b/gcc/config/aarch64/cortex-a57-fma-steering.cc
@@ -948,6 +948,11 @@ func_fma_steering::analyze ()
 
          /* Search the chain where this instruction is (one of) the root.  */
          dest_op_info = insn_rr[INSN_UID (insn)].op_info;
+
+         /* Register rename could fail. */
+         if (!dest_op_info)
+           continue;
+
          dest_regno = REGNO (SET_DEST (PATTERN (insn)));
          for (i = 0; i < dest_op_info->n_chains; i++)
            {
diff --git a/gcc/testsuite/g++.dg/torture/pr120119-1.C 
b/gcc/testsuite/g++.dg/torture/pr120119-1.C
new file mode 100644
index 000000000000..1206feb310be
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/pr120119-1.C
@@ -0,0 +1,15 @@
+// { dg-do compile }
+// { dg-additional-options "-mcpu=cortex-a57" { target aarch64*-*-* } }
+
+// PR target/120119
+
+struct a {
+  float operator()(int b, int c) { return d[c * 4 + b]; }
+  float *d;
+};
+float e(float *);
+auto f(a b) {
+  float g[]{b(1, 1), b(2, 1), b(3, 1), b(1, 2), b(2, 2), b(3, 2), b(1, 3),
+            b(2, 3), b(3, 3), b(3, 2), b(1, 3), b(2, 3), b(3, 3)};
+  return b.d[0] * e(g);
+}