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[COMMITTED,GCC,12] Fix PR 108582: ICE due to PHI-OPT removing a still in use ssa_name.

Message ID 20230207201959.1545413-1-apinski@marvell.com
State Unresolved
Headers
Series [COMMITTED,GCC,12] Fix PR 108582: ICE due to PHI-OPT removing a still in use ssa_name. |

Checks

Context Check Description
snail/gcc-patch-check warning Git am fail log

Commit Message

Andrew Pinski Feb. 7, 2023, 8:19 p.m. UTC 
  This patch adds a check in match_simplify_replacement to make sure the middlebb
does not have any phi-nodes as we don't currently move those.
This was just a thinko from before.

Committed on the GCC 12 branch after a bootstrap/test on x86_64-linux-gnu.

	PR tree-optimization/108582

gcc/ChangeLog:

	* tree-ssa-phiopt.cc (match_simplify_replacement): Add check
	for middlebb to have no phi nodes.

gcc/testsuite/ChangeLog:

	* gcc.dg/pr108582-1.c: New test.

(cherry picked from commit 876b3e0514bc8cb2256c44db56255403bedfa52d)
---
 gcc/testsuite/gcc.dg/pr108582-1.c | 58 +++++++++++++++++++++++++++++++
 gcc/tree-ssa-phiopt.cc            |  5 +++
 2 files changed, 63 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/pr108582-1.c
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Patch

diff --git a/gcc/testsuite/gcc.dg/pr108582-1.c b/gcc/testsuite/gcc.dg/pr108582-1.c
new file mode 100644
index 00000000000..88c2de369ad
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr108582-1.c
@@ -0,0 +1,58 @@ 
+/* { dg-do compile } */
+/* { dg-options "-O3 -fno-tree-ccp -fno-tree-dce" } */
+
+/*
+  PHI-OPT via match_simplify_replacement used to transform:
+  if (_25 != 0)
+    goto <bb 8>; [25.00%]
+  else
+    goto <bb 9>; [75.00%]
+
+  <bb 8> [local count: 11649864]:
+  # iftmp.5_13 = PHI <2(7)>
+  k_22 = k_11 | iftmp.5_13;
+
+  <bb 9> [local count: 105655256]:
+  # g_9 = PHI <1(2), 0(8), g_8(7)>
+  # k_12 = PHI <k_20(D)(2), k_22(8), k_11(7)>
+
+into:
+
+  _15 = (int) _25;
+  _28 = -_15;
+  _4 = _13 & _28;
+  _6 = _4 | k_11;
+
+  <bb 8> [local count: 105655256]:
+  # g_9 = PHI <1(2), g_8(7)>
+  # k_12 = PHI <k_20(D)(2), _6(7)>
+
+Removing the phi-node/assignment of _13.
+
+ */
+
+int a, c, d, e, f;
+char b;
+int main() {
+  int g = 1;
+  char h[1] = {0};
+  while (a) {
+    if (f) {
+      b = 0;
+      if (d)
+        continue;
+    }
+    if (a < 1) {
+      g = 0;
+      goto L;
+    }
+  }
+  while (c) {
+    char *j = h;
+    int k;
+  L:
+    if (e && !g)
+      k |= 2 | (*j < 0);
+  }
+  return 0;
+}
diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index 3eda825672c..b8e57bb470e 100644
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -973,6 +973,11 @@  match_simplify_replacement (basic_block cond_bb, basic_block middle_bb,
       if (!single_pred_p (middle_bb))
 	return false;
 
+      /* The middle bb cannot have phi nodes as we don't
+	 move those assignments yet. */
+      if (!gimple_seq_empty_p (phi_nodes (middle_bb)))
+	return false;
+
       stmt_to_move = last_and_only_stmt (middle_bb);
       if (!stmt_to_move)
 	return false;