i386: Fix ICE on __builtin_ia32_pabsd128 without lhs [PR112962]

The following patch fixes ICE on the testcase in similar way to how
other folded builtins are handled in ix86_gimple_fold_builtin when
they don't have a lhs; these builtins are const or pure, so normally
DCE would remove them later, but with -O0 that isn't guaranteed to
happen, and during expansion if they are marked TREE_SIDE_EFFECTS
it might still be attempted to be expanded.
This removes them right away during the folding.

Initially I wanted to also change all gsi_replace last args in that function
to true, but Andrew pointed to PR107209, so I've kept them as is.

2023-12-13  Jakub Jelinek  <jakub@redhat.com>

	PR target/112962
	* config/i386/i386.cc (ix86_gimple_fold_builtin): For shifts
	and abs without lhs replace with nop.

	* gcc.target/i386/pr112962.c: New test.

diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index 4706f0d40594ed7788abb4c66875eda2e06f742e..3e78949c7a661dc9eae1cd45301569fd5a3c95a6 100644 (file)
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -19377,7 +19377,10 @@ ix86_gimple_fold_builtin (gimple_stmt_iterator *gsi)
     do_shift:
       gcc_assert (n_args >= 2);
       if (!gimple_call_lhs (stmt))
-       break;
+       {
+         gsi_replace (gsi, gimple_build_nop (), false);
+         return true;
+       }
       arg0 = gimple_call_arg (stmt, 0);
       arg1 = gimple_call_arg (stmt, 1);
       elems = TYPE_VECTOR_SUBPARTS (TREE_TYPE (arg0));
@@ -19523,7 +19526,10 @@ ix86_gimple_fold_builtin (gimple_stmt_iterator *gsi)
     case IX86_BUILTIN_PABSD256_MASK:
       gcc_assert (n_args >= 1);
       if (!gimple_call_lhs (stmt))
-       break;
+       {
+         gsi_replace (gsi, gimple_build_nop (), false);
+         return true;
+       }
       arg0 = gimple_call_arg (stmt, 0);
       elems = TYPE_VECTOR_SUBPARTS (TREE_TYPE (arg0));
       /* For masked ABS, only optimize if the mask is all ones.  */

diff --git a/gcc/testsuite/gcc.target/i386/pr112962.c b/gcc/testsuite/gcc.target/i386/pr112962.c
new file mode 100644 (file)
index 0000000..8dfc0a6
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr112962.c
@@ -0,0 +1,11 @@
+/* PR target/112962 */
+/* { dg-do compile } */
+/* { dg-options "-fexceptions -mssse3" } */
+
+typedef int __attribute__((__vector_size__ (16))) V;
+
+void
+foo (void)
+{
+  __builtin_ia32_pabsd128 ((V) {});
+}