[gcc r13-9033] tree-optimization/115197 - fix ICE w/ constant in LC PHI and loop distribution

[Richard Biener]

https://gcc.gnu.org/g:062168c8bd4dbca659a5c6cc581f40e409f7d2ad

commit r13-9033-g062168c8bd4dbca659a5c6cc581f40e409f7d2ad
Author: Richard Biener <rguenther@suse.de>
Date:   Thu May 23 14:36:39 2024 +0200

    tree-optimization/115197 - fix ICE w/ constant in LC PHI and loop distribution
    
    Forgot a check for an SSA name before trying to replace a PHI arg with
    its current definition.
    
            PR tree-optimization/115197
            * tree-loop-distribution.cc (copy_loop_before): Constant PHI
            args remain the same.
    
            * gcc.dg/pr115197.c: New testcase.
    
    (cherry picked from commit 2b2476d4d18c92b8aba3567ebccd2100c2f7c258)

Diff:
---
 gcc/testsuite/gcc.dg/pr115197.c | 14 ++++++++++++++
 gcc/tree-loop-distribution.cc   |  7 +++++--
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/gcc/testsuite/gcc.dg/pr115197.c b/gcc/testsuite/gcc.dg/pr115197.c
new file mode 100644
index 000000000000..00d674b3bd9a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr115197.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fno-tree-scev-cprop -ftree-pre -ftree-loop-distribute-patterns" } */
+
+int a, b[2], c, d, e, f[2];
+int main() {
+  while (a)
+    if (d) {
+      if (e)
+        return 0;
+      for (; c; c++)
+        f[c] = 0 < (b[c] = ~(f[c + 1] < a));
+    }
+  return 0;
+}
diff --git a/gcc/tree-loop-distribution.cc b/gcc/tree-loop-distribution.cc
index 3d92d1c73b5f..907610d56704 100644
--- a/gcc/tree-loop-distribution.cc
+++ b/gcc/tree-loop-distribution.cc
@@ -963,8 +963,11 @@ copy_loop_before (class loop *loop, bool redirect_lc_phi_defs)
 	  if (virtual_operand_p (gimple_phi_result (phi)))
 	    continue;
 	  use_operand_p use_p = PHI_ARG_DEF_PTR_FROM_EDGE (phi, exit);
-	  tree new_def = get_current_def (USE_FROM_PTR (use_p));
-	  SET_USE (use_p, new_def);
+	  if (TREE_CODE (USE_FROM_PTR (use_p)) == SSA_NAME)
+	    {
+	      tree new_def = get_current_def (USE_FROM_PTR (use_p));
+	      SET_USE (use_p, new_def);
+	    }
 	}
     }