Hi!
The documentation for POST_MODIFY says:
Currently, the compiler can only handle second operands of the
form (plus (reg) (reg)) and (plus (reg) (const_int)), where
the first operand of the PLUS has to be the same register as
the first operand of the *_MODIFY.
The following testcase ICEs, because combine just attempts to simplify
things and ends up with
(post_modify (reg1) (plus (mult (reg2) (const_int 4)) (reg1))
but the target predicates accept it, because they only verify
that POST_MODIFY's second operand is PLUS and the second operand
of the PLUS is a REG.
The following patch fixes this by performing further verification that
the POST_MODIFY is in the form it should be.
Bootstrapped/regtested on armv7hl-linux-gnueabi, ok for trunk
and release branches after a while?
2020-11-19 Jakub Jelinek <ja...@redhat.com>
PR target/97528
* config/arm/arm.c (neon_vector_mem_operand): For POST_MODIFY, require
first POST_MODIFY operand is a REG and is equal to the first operand
of PLUS.
* gcc.target/arm/pr97528.c: New test.
--- gcc/config/arm/arm.c.jj 2020-11-13 19:00:46.729620560 +0100
+++ gcc/config/arm/arm.c 2020-11-18 17:05:44.656867343 +0100
@@ -13429,7 +13429,9 @@ neon_vector_mem_operand (rtx op, int typ
/* Allow post-increment by register for VLDn */
if (type == 2 && GET_CODE (ind) == POST_MODIFY
&& GET_CODE (XEXP (ind, 1)) == PLUS
- && REG_P (XEXP (XEXP (ind, 1), 1)))
+ && REG_P (XEXP (XEXP (ind, 1), 1))
+ && REG_P (XEXP (ind, 0))
+ && rtx_equal_p (XEXP (ind, 0), XEXP (XEXP (ind, 1), 0)))
return true;
/* Match:
--- gcc/testsuite/gcc.target/arm/pr97528.c.jj 2020-11-18 17:09:58.195053288
+0100
+++ gcc/testsuite/gcc.target/arm/pr97528.c 2020-11-18 17:09:47.839168237
+0100
@@ -0,0 +1,28 @@
+/* PR target/97528 */
+/* { dg-do compile } */
+/* { dg-require-effective-target arm_neon_ok } */
+/* { dg-options "-O1" } */
+/* { dg-add-options arm_neon } */
+
+#include <arm_neon.h>
+
+typedef __simd64_int16_t T;
+typedef __simd64_uint16_t U;
+unsigned short c;
+int d;
+U e;
+
+void
+foo (void)
+{
+ unsigned short *dst = &c;
+ int g = d, b = 4;
+ U dc = e;
+ for (int h = 0; h < b; h++)
+ {
+ unsigned short *i = dst;
+ U j = dc;
+ vst1_s16 ((int16_t *) i, (T) j);
+ dst += g;
+ }
+}
Jakub
