[PATCH] MIPS: Support constraint 'w' for MSA instruction

[YunQiang Su]

Support syntax like:
        asm volatile ("fmadd.d %w0, %w1, %w2" : "+w"(a): "w"(b), "w"(c));

gcc
        * config/mips/constraints.md: Add new constraint 'w'.

gcc/testsuite
        * gcc.target/mips/msa-inline-asm.c: New test.
---
 gcc/config/mips/constraints.md                 | 3 +++
 gcc/testsuite/gcc.target/mips/msa-inline-asm.c | 9 +++++++++
 2 files changed, 12 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/mips/msa-inline-asm.c

diff --git a/gcc/config/mips/constraints.md b/gcc/config/mips/constraints.md
index a96028dd746..f5c88179038 100644
--- a/gcc/config/mips/constraints.md
+++ b/gcc/config/mips/constraints.md
@@ -29,6 +29,9 @@ (define_register_constraint "t" "T_REG"
 (define_register_constraint "f" "TARGET_HARD_FLOAT ? FP_REGS : NO_REGS"
   "A floating-point register (if available).")
 
+(define_register_constraint "w" "ISA_HAS_MSA ? FP_REGS : NO_REGS"
+  "A MIPS SIMD register (if available).")
+
 (define_register_constraint "h" "NO_REGS"
   "Formerly the @code{hi} register.  This constraint is no longer supported.")
 
diff --git a/gcc/testsuite/gcc.target/mips/msa-inline-asm.c 
b/gcc/testsuite/gcc.target/mips/msa-inline-asm.c
new file mode 100644
index 00000000000..bdf6816ab3b
--- /dev/null
+++ b/gcc/testsuite/gcc.target/mips/msa-inline-asm.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-mno-mips16 -mfp64 -mhard-float -mmsa" } */
+
+double
+f(double a, double b, double c) {
+  asm volatile ("fmadd.d %w0, %w1, %w2" : "+w"(a): "w"(b), "w"(c));
+  return a;
+}
+/* { dg-final { scan-assembler "fmadd.d \\\$w0, \\\$w\[0-9\]*, \\\$w\[0-9\]*" 
} }  */
-- 
2.39.2