[gcc r12-10546] PHIOPT: Don't transform minmax if middle bb contains a phi [PR115143]

[Andrew Pinski]

https://gcc.gnu.org/g:d30afaae6764379a63c22459b40aaecfa82b0fc4

commit r12-10546-gd30afaae6764379a63c22459b40aaecfa82b0fc4
Author: Andrew Pinski <quic_apinski@quicinc.com>
Date:   Sat May 18 11:55:58 2024 -0700

    PHIOPT: Don't transform minmax if middle bb contains a phi [PR115143]
    
    The problem here is even if last_and_only_stmt returns a statement,
    the bb might still contain a phi node which defines a ssa name
    which is used in that statement so we need to add a check to make sure
    that the phi nodes are empty for the middle bbs in both the
    `CMP?MINMAX:MINMAX` case and the `CMP?MINMAX:B` cases.
    
    Bootstrapped and tested on x86_64_linux-gnu with no regressions.
    
            PR tree-optimization/115143
    
    gcc/ChangeLog:
    
            * tree-ssa-phiopt.cc (minmax_replacement): Check for empty
            phi nodes for middle bbs for the case where middle bb is not empty.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.c-torture/compile/pr115143-1.c: New test.
            * gcc.c-torture/compile/pr115143-2.c: New test.
            * gcc.c-torture/compile/pr115143-3.c: New test.
    
    Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
    (cherry picked from commit 9ff8f041331ef8b56007fb3c4d41d76f9850010d)

Diff:
---
 gcc/testsuite/gcc.c-torture/compile/pr115143-1.c | 21 +++++++++++++++++
 gcc/testsuite/gcc.c-torture/compile/pr115143-2.c | 30 ++++++++++++++++++++++++
 gcc/testsuite/gcc.c-torture/compile/pr115143-3.c | 29 +++++++++++++++++++++++
 gcc/tree-ssa-phiopt.cc                           |  4 ++++
 4 files changed, 84 insertions(+)

diff --git a/gcc/testsuite/gcc.c-torture/compile/pr115143-1.c b/gcc/testsuite/gcc.c-torture/compile/pr115143-1.c
new file mode 100644
index 000000000000..5cb119ea4325
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr115143-1.c
@@ -0,0 +1,21 @@
+/* PR tree-optimization/115143 */
+/* This used to ICE.
+   minmax part of phiopt would transform,
+   would transform `a!=0?min(a, b) : 0` into `min(a,b)`
+   which was correct except b was defined by a phi in the inner
+   bb which was not handled. */
+short a, d;
+char b;
+long c;
+unsigned long e, f;
+void g(unsigned long h) {
+  if (c ? e : b)
+    if (e)
+      if (d) {
+        a = f ? ({
+          unsigned long i = d ? f : 0, j = e ? h : 0;
+          i < j ? i : j;
+        }) : 0;
+      }
+}
+
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr115143-2.c b/gcc/testsuite/gcc.c-torture/compile/pr115143-2.c
new file mode 100644
index 000000000000..05c3bbe9738e
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr115143-2.c
@@ -0,0 +1,30 @@
+/* { dg-options "-fgimple" } */
+/* PR tree-optimization/115143 */
+/* This used to ICE.
+   minmax part of phiopt would transform,
+   would transform `a!=0?min(a, b) : 0` into `min(a,b)`
+   which was correct except b was defined by a phi in the inner
+   bb which was not handled. */
+unsigned __GIMPLE (ssa,startwith("phiopt"))
+foo (unsigned a, unsigned b)
+{
+  unsigned j;
+  unsigned _23;
+  unsigned _12;
+
+  __BB(2):
+  if (a_6(D) != 0u)
+    goto __BB3;
+  else
+    goto __BB4;
+
+  __BB(3):
+  j_10 = __PHI (__BB2: b_11(D));
+  _23 = __MIN (a_6(D), j_10);
+  goto __BB4;
+
+  __BB(4):
+  _12 = __PHI (__BB3: _23, __BB2: 0u);
+  return _12;
+
+}
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr115143-3.c b/gcc/testsuite/gcc.c-torture/compile/pr115143-3.c
new file mode 100644
index 000000000000..53c5fb5588e9
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr115143-3.c
@@ -0,0 +1,29 @@
+/* { dg-options "-fgimple" } */
+/* PR tree-optimization/115143 */
+/* This used to ICE.
+   minmax part of phiopt would transform,
+   would transform `a!=0?min(a, b) : 0` into `min(a,b)`
+   which was correct except b was defined by a phi in the inner
+   bb which was not handled. */
+unsigned __GIMPLE (ssa,startwith("phiopt"))
+foo (unsigned a, unsigned b)
+{
+  unsigned j;
+  unsigned _23;
+  unsigned _12;
+
+  __BB(2):
+  if (a_6(D) > 0u)
+    goto __BB3;
+  else
+    goto __BB4;
+
+  __BB(3):
+  j_10 = __PHI (__BB2: b_7(D));
+  _23 = __MIN (a_6(D), j_10);
+  goto __BB4;
+
+  __BB(4):
+  _12 = __PHI (__BB3: _23, __BB2: 0u);
+  return _12;
+}
diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index e2dba56383b4..558d5b4b57db 100644
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -1973,6 +1973,10 @@ minmax_replacement (basic_block cond_bb, basic_block middle_bb,
 	  || gimple_code (assign) != GIMPLE_ASSIGN)
 	return false;
 
+      /* There cannot be any phi nodes in the middle bb. */
+      if (!gimple_seq_empty_p (phi_nodes (middle_bb)))
+	return false;
+
       lhs = gimple_assign_lhs (assign);
       ass_code = gimple_assign_rhs_code (assign);
       if (ass_code != MAX_EXPR && ass_code != MIN_EXPR)