[gcc r11-7929] arm: Fix mult autovectorization patterm for iwmmxt (PR target/99786)

[gcc r11-7929] arm: Fix mult autovectorization patterm for iwmmxt (PR target/99786)

[Christophe Lyon]

https://gcc.gnu.org/g:7c1d6e89994109e1b6efb5f13890be5586edeb75

commit r11-7929-g7c1d6e89994109e1b6efb5f13890be5586edeb75
Author: Christophe Lyon <christophe.lyon@linaro.org>
Date:   Mon Mar 29 12:41:08 2021 +0000

    arm: Fix mult autovectorization patterm for iwmmxt (PR target/99786)
    
    Similarly to other recently-added autovectorization patterns, mult has
    been erroneously enabled for iwmmxt. However, V4HI and V2SI modes are
    supported, so we make an exception for them.
    
    The new testcase is derived from gcc.dg/ubsan/pr79904.c, with
    additional modes added.
    
    I kept dg-do compile because 'assemble' results in error messages from
    the assembler, which are not related to this PR:
    
    Error: selected processor does not support `tmcrr wr0,r4,r5' in ARM mode
    Error: selected processor does not support `wstrd wr0,[r0]' in ARM mode
    Error: selected processor does not support `wldrd wr0,[r0]' in ARM mode
    Error: selected processor does not support `wldrd wr2,.L5' in ARM mode
    Error: selected processor does not support `wmulul wr0,wr0,wr2' in ARM mode
    Error: selected processor does not support `wstrd wr0,[r0]' in ARM mode
    Error: selected processor does not support `wldrd wr0,[r0]' in ARM mode
    Error: selected processor does not support `wldrd wr2,.L8' in ARM mode
    Error: selected processor does not support `wmulwl wr0,wr0,wr2' in ARM mode
    Error: selected processor does not support `wstrd wr0,[r0]' in ARM mode
    
    2021-03-29  Christophe Lyon  <christophe.lyon@linaro.org>
    
            PR target/99786
    
            gcc/
            * config/arm/vec-common.md (mul<mode>3): Disable on iwMMXT, expect
            for V4HI and V2SI.
    
            gcc/testsuite/
            * gcc.target/arm/pr99786.c: New test.

Diff:
---
 gcc/config/arm/vec-common.md           |  5 ++++-
 gcc/testsuite/gcc.target/arm/pr99786.c | 30 ++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/gcc/config/arm/vec-common.md b/gcc/config/arm/vec-common.md
index 48ee6593cca..0b2b3b1c9ce 100644
--- a/gcc/config/arm/vec-common.md
+++ b/gcc/config/arm/vec-common.md
@@ -103,7 +103,10 @@
   [(set (match_operand:VDQWH 0 "s_register_operand")
 	(mult:VDQWH (match_operand:VDQWH 1 "s_register_operand")
 		    (match_operand:VDQWH 2 "s_register_operand")))]
-  "ARM_HAVE_<MODE>_ARITH"
+  "ARM_HAVE_<MODE>_ARITH
+   && (!TARGET_REALLY_IWMMXT
+       || <MODE>mode == V4HImode
+       || <MODE>mode == V2SImode)"
 )
 
 (define_expand "smin<mode>3"
diff --git a/gcc/testsuite/gcc.target/arm/pr99786.c b/gcc/testsuite/gcc.target/arm/pr99786.c
new file mode 100644
index 00000000000..11d86f09d12
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/pr99786.c
@@ -0,0 +1,30 @@
+/* { dg-do compile } */
+/* { dg-skip-if "Test is specific to the iWMMXt" { arm*-*-* } { "-mcpu=*" } { "-mcpu=iwmmxt" } } */
+/* { dg-skip-if "Test is specific to the iWMMXt" { arm*-*-* } { "-mabi=*" } { "-mabi=iwmmxt" } } */
+/* { dg-skip-if "Test is specific to the iWMMXt" { arm*-*-* } { "-march=*" } { "-march=iwmmxt" } } */
+/* { dg-skip-if "Test is specific to ARM mode" { arm*-*-* } { "-mthumb" } { "" } } */
+/* { dg-require-effective-target arm32 } */
+/* { dg-require-effective-target arm_iwmmxt_ok } */
+/* { dg-options "-O3 -mcpu=iwmmxt" } */
+
+typedef signed char V __attribute__((vector_size (8))); 
+
+void
+foo (V *a) 
+{ 
+  *a = *a * 3; 
+}
+
+typedef signed short Vshort __attribute__((vector_size (8))); 
+void
+foo_short (Vshort *a) 
+{ 
+  *a = *a * 3; 
+}
+
+typedef signed int Vint __attribute__((vector_size (8))); 
+void
+foo_int (Vint *a) 
+{ 
+  *a = *a * 3; 
+}