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>

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 (file)
index 0000000..5cb119e
--- /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 (file)
index 0000000..05c3bbe
--- /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 (file)
index 0000000..53c5fb5
--- /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 f166c3132cb7e6e2a382ed4aef0893f98739b267..918cf50b58984db1e0f84a8f27a9053ca9e0a6fb 100644 (file)
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -1925,6 +1925,10 @@ minmax_replacement (basic_block cond_bb, basic_block middle_bb, basic_block alt_
          || 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)
@@ -1938,6 +1942,10 @@ minmax_replacement (basic_block cond_bb, basic_block middle_bb, basic_block alt_
          || gimple_code (assign) != GIMPLE_ASSIGN)
        return false;
 
+      /* There cannot be any phi nodes in the alt middle bb. */
+      if (!gimple_seq_empty_p (phi_nodes (alt_middle_bb)))
+       return false;
+
       alt_lhs = gimple_assign_lhs (assign);
       if (ass_code != gimple_assign_rhs_code (assign))
        return false;
@@ -2049,6 +2057,10 @@ minmax_replacement (basic_block cond_bb, basic_block middle_bb, basic_block alt_
          || 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)