[SPARC] Fix PR target/81988

[Eric Botcazou]

This is a regression present on the mainline and 7 branch: when the register 
pressure is high, the use of DI/SI paradoxical subregs causes LRA to generate 
invalid accesses to odd-numbered FP registers when registers are spilled.

The attached patch is aimed at drying up a big source of DI/SI paradoxical 
subregs, namely 32-bit multiplication operations.

Tested on SPARC64/Linux, applied on mainline and 7 branch.


2017-09-08  Eric Botcazou  <ebotca...@adacore.com>

        PR target/81988
        * config/sparc/sparc.md (mulsi3): Rename into *mulsi3_sp32.
        (*mulsi3_sp64): New instruction.
        (mulsi3): New expander.


2017-09-08  Eric Botcazou  <ebotca...@adacore.com>

        * gcc.dg/pr81988.c: New test.

-- 
Eric Botcazou
Index: config/sparc/sparc.md
===================================================================
--- config/sparc/sparc.md	(revision 251861)
+++ config/sparc/sparc.md	(working copy)
@@ -4517,7 +4517,14 @@ (define_insn "*cmp_ccv_minus_sltu_set"
 ;; The 32-bit multiply/divide instructions are deprecated on v9, but at
 ;; least in UltraSPARC I, II and IIi it is a win tick-wise.
 
-(define_insn "mulsi3"
+(define_expand "mulsi3"
+  [(set (match_operand:SI 0 "register_operand" "")
+	(mult:SI (match_operand:SI 1 "arith_operand" "")
+		 (match_operand:SI 2 "arith_operand" "")))]
+  "TARGET_HARD_MUL || TARGET_ARCH64"
+  "")
+
+(define_insn "*mulsi3_sp32"
   [(set (match_operand:SI 0 "register_operand" "=r")
 	(mult:SI (match_operand:SI 1 "arith_operand" "%r")
 		 (match_operand:SI 2 "arith_operand" "rI")))]
@@ -4525,6 +4532,14 @@ (define_insn "mulsi3"
   "smul\t%1, %2, %0"
   [(set_attr "type" "imul")])
 
+(define_insn "*mulsi3_sp64"
+  [(set (match_operand:SI 0 "register_operand" "=r")
+	(mult:SI (match_operand:SI 1 "arith_operand" "%r")
+		 (match_operand:SI 2 "arith_operand" "rI")))]
+  "TARGET_ARCH64"
+  "mulx\t%1, %2, %0"
+  [(set_attr "type" "imul")])
+
 (define_expand "muldi3"
   [(set (match_operand:DI 0 "register_operand" "")
 	(mult:DI (match_operand:DI 1 "arith_operand" "")

/* PR target/81988 */
/* Testcase by James Cowgill <jcowgill+...@jcowgill.uk> */

/* { dg-do assemble } */
/* { dg-require-effective-target pie } */
/* { dg-options "-O3 -fpie" } */

int c, d;

short **e;
int *a;

void foo(void)
{
  int g[64 * 35], *h = g;
  do {
    short *f = e[d];
    for (int i = 0; i < 4; i++)
      a[i] = a[i] + (h[364] + f[4] * h[64] + f[5] * h[i] + f[6] * h[i + 3 * 4] +
                     f[7] * h[i + 4]);
  } while (c);
}