From: Gabriel Dos Reis <gdr@integrable-solutions.net>
Date: Sat, 13 Mar 2004 00:30:53 +0000 (+0000)
Subject: re PR rtl-optimization/13472 (optimizer generates code to store data in const int... 
X-Git-Tag: releases/gcc-3.3.4~170
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ac136059cb4d4d889bc50f5e58d306eb2cef2a6e;p=thirdparty%2Fgcc.git

re PR rtl-optimization/13472 (optimizer generates code to store data in const int, resulting in a segfault)

        Endorse:
        2004-01-10  Eric Botcazou  <ebotcazou@libertysurf.fr>
        PR optimization/13472
        * reload.c (reload): Don't record unchanging memory locations.

From-SVN: r79421
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index aa6bd0a2f83b..6583ae2246f0 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2004-03-12  Gabriel Dos Reis  <gdr@integrable-solutions.net>
+        
+        Endorse:
+	2004-01-10  Eric Botcazou  <ebotcazou@libertysurf.fr>
+	PR optimization/13472
+	* reload.c (reload): Don't record unchanging memory locations.
+
 2004-03-12  Gabriel Dos Reis  <gdr@integrable-solutions.net>
 
 	Backport
diff --git a/gcc/reload1.c b/gcc/reload1.c
index edab53a0e85a..c747ddf7297d 100644
--- a/gcc/reload1.c
+++ b/gcc/reload1.c
@@ -789,8 +789,18 @@ reload (first, global)
 		     that is not a legitimate memory operand.  As later
 		     stages of reload assume that all addresses found
 		     in the reg_equiv_* arrays were originally legitimate,
-		     we ignore such REG_EQUIV notes.  */
-		  if (memory_operand (x, VOIDmode))
+		     we ignore such REG_EQUIV notes.
+
+		     It also can happen that a REG_EQUIV note contains a MEM
+		     that carries the /u flag, for example when GCSE turns
+		     the load of a constant into a move from a pseudo that
+		     already contains the constant and attaches a REG_EQUAL
+		     note to the insn, which is later promoted to REQ_EQUIV
+		     by local-alloc.  If the destination pseudo happens not
+		     to be assigned to a hard reg, it will be replaced by
+		     the MEM as the destination of the move, thus generating
+		     a store to a possibly read-only memory location.  */
+		  if (memory_operand (x, VOIDmode) && ! RTX_UNCHANGING_P (x))
 		    {
 		      /* Always unshare the equivalence, so we can
 			 substitute into this insn without touching the
diff --git a/gcc/testsuite/gcc.dg/const-1.c b/gcc/testsuite/gcc.dg/const-1.c
new file mode 100644
index 000000000000..40678c6431ce
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/const-1.c
@@ -0,0 +1,56 @@
+/* PR optimization/13472 */
+/* Origin: <p.van-hoof@qub.ac.uk> */
+
+/* Verify that the reload pass doesn't emit a store
+   to the .rodata section. */
+
+/* { dg-do run } */
+/* { dg-options "-O2 -pedantic -march=i686" { target i686-*-* } } */
+
+
+#define MAX2(a,b) (((a)>(b)) ? (a) : (b))
+
+const int q=0, p=0;
+
+typedef struct {
+	float a;
+	float b;
+} F;
+
+F **E, *D, C = { 2.f, 1.f };
+
+void G(float);
+void H(void);
+
+int main(void)
+{
+	D = &C;
+	E = &D;
+
+	H();
+        return 0;
+}
+
+void H(void)
+{
+	int i, l=1;
+	float b, o;
+
+	if( l )
+	{
+		b = 0.3f * MAX2(0.f,E[q][p].a - E[q][p].b);
+		o = E[q][p].a;
+		if( o > 1.e-36f )
+                        G(o);
+		E[q][p].a *= b;
+	}
+	else
+		b = 1.f;
+	for( i=q; i<2; ++i )
+		;
+}
+
+void G(float o)
+{
+}
+