[PATCH][simplify-rtx]: Fix incorrect folding of shift and AND [PR117012]

[Tamar Christina]

Hi All,

The optimization added in r15-1047-g7876cde25cbd2f is using the wrong
operaiton to check for uniform constant vectors.

The Author intended to check that all the lanes in the vector are the same and
so used CONST_VECTOR_DUPLICATE_P.  However this only checks that the vector
is created from a pattern duplication, but doesn't say how many pattern
alternatives make up the duplication.  Normally would would need to check this
separately or use const_vec_duplicate_p.

Without this the optimization incorrectly triggers.

Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.

Ok for master?

Thanks,
Tamar

gcc/ChangeLog:

	PR rtl-optimization/117012
	* simplify-rtx.cc (simplify_context::simplify_binary_operation_1): Use
	const_vec_duplicate_p instead of CONST_VECTOR_DUPLICATE_P.

gcc/testsuite/ChangeLog:

	PR rtl-optimization/117012
	* gcc.target/aarch64/pr117012.c: New test.

---
diff --git a/gcc/simplify-rtx.cc b/gcc/simplify-rtx.cc
index e8e60404ef62b891a68bc68645c4c349a1b12a7c..c304baa3c3ab6ada95b85961f34532966428e337 100644
--- a/gcc/simplify-rtx.cc
+++ b/gcc/simplify-rtx.cc
@@ -4084,10 +4084,10 @@ simplify_context::simplify_binary_operation_1 (rtx_code code,
       if (VECTOR_MODE_P (mode) && GET_CODE (op0) == ASHIFTRT
 	  && (CONST_INT_P (XEXP (op0, 1))
 	      || (GET_CODE (XEXP (op0, 1)) == CONST_VECTOR
-		  && CONST_VECTOR_DUPLICATE_P (XEXP (op0, 1))
+		  && const_vec_duplicate_p (XEXP (op0, 1))
 		  && CONST_INT_P (XVECEXP (XEXP (op0, 1), 0, 0))))
 	  && GET_CODE (op1) == CONST_VECTOR
-	  && CONST_VECTOR_DUPLICATE_P (op1)
+	  && const_vec_duplicate_p (op1)
 	  && CONST_INT_P (XVECEXP (op1, 0, 0)))
 	{
 	  unsigned HOST_WIDE_INT shift_count
diff --git a/gcc/testsuite/gcc.target/aarch64/pr117012.c b/gcc/testsuite/gcc.target/aarch64/pr117012.c
new file mode 100644
index 0000000000000000000000000000000000000000..537c0fa566c6c930ebad3013e3adea9e9fdd1a23
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/pr117012.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+#define vector16 __attribute__((vector_size(16)))
+
+vector16 unsigned char
+g (vector16 unsigned char a)
+{
+  vector16 signed char b = (vector16 signed char)a;
+  b = b >> 7;
+  vector16 unsigned char c = (vector16 unsigned char)b;
+  vector16 unsigned char d = { 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0 };
+  return c & d;
+}
+
+/* { dg-final { scan-assembler-times {and\tv[0-9]+\.16b, v[0-9]+\.16b, v[0-9]+\.16b} 1 } } */




-- 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: rb18848.patch
Type: text/x-diff
Size: 1571 bytes
Desc: not available
URL: <https://gcc.gnu.org/pipermail/gcc-patches/attachments/20241014/a865dccf/attachment-0001.bin>