Fix 70278 (LRA split_regs followup patch)

[Bernd Schmidt <bschmidt@redhat.com>]

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This fixes an oversight in my previous patch here. I used biggest_mode 
in the assumption that if the reg was used in the function, it would be 
set to something other than VOIDmode, but that fails if we have a 
multiword access - only the first hard reg gets its biggest_mode 
assigned in that case.

Bootstrapped and tested on x86_64-linux, ran (just) the new arm testcase 
manually with arm-eabi. Ok?

(The testcase seems to be from glibc. Do we keep the copyright notices 
on the reduced form)?


Bernd

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	PR rtl-optimization/70278
	* lra-constraints.c (split_reg): Handle the case where biggest_mode is
	VOIDmode.

testsuite/
	* gcc.dg/torture/pr70278.c: New test.
	* gcc.target/arm/pr70278.c: New test.

Index: gcc/lra-constraints.c
===================================================================
--- gcc/lra-constraints.c	(revision 234184)
+++ gcc/lra-constraints.c	(working copy)
@@ -4982,7 +4982,12 @@ split_reg (bool before_p, int original_r
       nregs = 1;
       mode = lra_reg_info[hard_regno].biggest_mode;
       machine_mode reg_rtx_mode = GET_MODE (regno_reg_rtx[hard_regno]);
-      if (GET_MODE_SIZE (mode) > GET_MODE_SIZE (reg_rtx_mode))
+      /* A reg can have a biggest_mode of VOIDmode if it was only ever seen
+	 as part of a multi-word register.  In that case, or if the biggest
+	 mode was larger than a register, just use the reg_rtx.  Otherwise,
+	 limit the size to that of the biggest access in the function.  */
+      if (mode == VOIDmode
+	  || GET_MODE_SIZE (mode) > GET_MODE_SIZE (reg_rtx_mode))
 	{
 	  original_reg = regno_reg_rtx[hard_regno];
 	  mode = reg_rtx_mode;
Index: gcc/testsuite/gcc.dg/torture/pr70278.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr70278.c	(revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr70278.c	(working copy)
@@ -0,0 +1,37 @@
+/* { dg-do compile } */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice 
+ * is preserved.
+ * ====================================================
+ */
+typedef union
+{
+  double value;
+  struct
+  {
+    unsigned int msw;
+  } parts;
+} ieee_double_shape_type;
+double __ieee754_hypot(double x, double y)
+{
+ double a=x,b=y,t1,t2,y1,y2,w;
+ int j,k,ha,hb;
+ do { ieee_double_shape_type gh_u; gh_u.value = (x); (ha) = gh_u.parts.msw; } while (0);;
+ if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;}
+ if(ha > 0x5f300000) {
+    do { ieee_double_shape_type sh_u; sh_u.value = (a); sh_u.parts.msw = (ha); (a) = sh_u.value; } while (0);;
+ }
+ w = a-b;
+ if (w <= b)
+ {
+     t2 = a - t1;
+     w = t1*y1-(w*(-w)-(t1*y2+t2*b));
+ }
+ if(k!=0) {
+ } else return w;
+}
Index: gcc/testsuite/gcc.target/arm/pr70278.c
===================================================================
--- gcc/testsuite/gcc.target/arm/pr70278.c	(revision 0)
+++ gcc/testsuite/gcc.target/arm/pr70278.c	(working copy)
@@ -0,0 +1,41 @@
+/* { dg-do compile } */
+/* { dg-skip-if "avoid conflicting multilib options" { *-*-* } { "-march=*" } { "-march=armv4t" } } */
+/* { dg-skip-if "avoid conflicting multilib options" { *-*-* } { "-marm" } { "" } } */
+/* { dg-options "-mthumb" } */
+/* { dg-add-options arm_arch_v4t } */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice 
+ * is preserved.
+ * ====================================================
+ */
+typedef union
+{
+  double value;
+  struct
+  {
+    unsigned int msw;
+  } parts;
+} ieee_double_shape_type;
+double __ieee754_hypot(double x, double y)
+{
+ double a=x,b=y,t1,t2,y1,y2,w;
+ int j,k,ha,hb;
+ do { ieee_double_shape_type gh_u; gh_u.value = (x); (ha) = gh_u.parts.msw; } while (0);;
+ if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;}
+ if(ha > 0x5f300000) {
+    do { ieee_double_shape_type sh_u; sh_u.value = (a); sh_u.parts.msw = (ha); (a) = sh_u.value; } while (0);;
+ }
+ w = a-b;
+ if (w <= b)
+ {
+     t2 = a - t1;
+     w = t1*y1-(w*(-w)-(t1*y2+t2*b));
+ }
+ if(k!=0) {
+ } else return w;
+}