re PR rtl-optimization/25703 (ACATS cxa4024 failure)

	PR rtl-optimization/25703
	* combine.c (try_combine): Handle zero_extract and strict_low_part
	of non-lowpart SUBREGs for constant reg_subword_p set optimization.

	* gcc.target/i386/20060125-1.c: New test case.
	* gcc.target/i386/20060125-2.c: New test case.

From-SVN: r110242

5 files changed, 91 insertions, 20 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 370f701..df995ab 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2006-01-25  Roger Sayle  <roger@eyesopen.com>
+
+	PR rtl-optimization/25703
+	* combine.c (try_combine): Handle zero_extract and strict_low_part
+	of non-lowpart SUBREGs for constant reg_subword_p set optimization.
+
 2006-01-25  Peter Bergner  <bergner@vnet.ibm.com>
 
 	* global.c: Fix comment typos.
diff --git a/gcc/combine.c b/gcc/combine.c
index 0ec4580..2c90be5 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -1951,40 +1951,38 @@ try_combine (rtx i3, rtx i2, rtx i1, int *new_direct_jump_p)
       int offset = -1;
       int width = 0;
 
-      if (GET_CODE (dest) == STRICT_LOW_PART)
-	{
-	  width = GET_MODE_BITSIZE (GET_MODE (XEXP (dest, 0)));
-	  offset = 0;
-	}
-      else if (GET_CODE (dest) == ZERO_EXTRACT)
+      if (GET_CODE (dest) == ZERO_EXTRACT)
 	{
 	  if (GET_CODE (XEXP (dest, 1)) == CONST_INT
 	      && GET_CODE (XEXP (dest, 2)) == CONST_INT)
 	    {
 	      width = INTVAL (XEXP (dest, 1));
 	      offset = INTVAL (XEXP (dest, 2));
-
+	      dest = XEXP (dest, 0);
 	      if (BITS_BIG_ENDIAN)
-		offset = GET_MODE_BITSIZE (GET_MODE (XEXP (dest, 0)))
-			 - width - offset;
+		offset = GET_MODE_BITSIZE (GET_MODE (dest)) - width - offset;
 	    }
 	}
-      else if (subreg_lowpart_p (dest))
+      else
 	{
+	  if (GET_CODE (dest) == STRICT_LOW_PART)
+	    dest = XEXP (dest, 0);
 	  width = GET_MODE_BITSIZE (GET_MODE (dest));
 	  offset = 0;
 	}
-      /* ??? Preserve the original logic to handle setting the high word
-	 of double-word pseudos, where inner is half the size of outer
-	 but not the lowpart.  This could be generalized by handling
-	 SUBREG_BYTE, WORDS_BIG_ENDIAN and BYTES_BIG_ENDIAN ourselves.
-	 Unfortunately this logic is tricky to get right and probably
-	 not worth the effort.  */
-      else if (GET_MODE_BITSIZE (GET_MODE (SET_DEST (temp)))
-	       == 2 * GET_MODE_BITSIZE (GET_MODE (dest)))
+
+      if (offset >= 0)
 	{
-	  width = GET_MODE_BITSIZE (GET_MODE (dest));
-	  offset = width;
+	  /* If this is the low part, we're done.  */
+	  if (subreg_lowpart_p (dest))
+	    ;
+	  /* Handle the case where inner is twice the size of outer.  */
+	  else if (GET_MODE_BITSIZE (GET_MODE (SET_DEST (temp)))
+		   == 2 * GET_MODE_BITSIZE (GET_MODE (dest)))
+	    offset += GET_MODE_BITSIZE (GET_MODE (dest));
+	  /* Otherwise give up for now.  */
+	  else
+	    offset = -1;
 	}
 
       if (offset >= 0)
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 28d3297..075def5 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2006-01-25  Jan Hubicka  <jh@suse.cz>
+	    Roger Sayle  <roger@eyesopen.com>
+
+	PR rtl-optimization/25703
+	* gcc.target/i386/20060125-1.c: New test case.
+	* gcc.target/i386/20060125-2.c: New test case.
+
 2006-01-25  Tobias Schlüter  <tobias.schlueter@physik.uni-muenchen.de>
 
 	PR fortran/18540
diff --git a/gcc/testsuite/gcc.target/i386/20060125-1.c b/gcc/testsuite/gcc.target/i386/20060125-1.c
new file mode 100644
index 0000000..cbb4e65
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/20060125-1.c
@@ -0,0 +1,30 @@
+/* PR rtl-optimization/25703 */
+/* { dg-do run { target i?86-*-* x86_64-*-* } } */
+/* { dg-require-effective-target ilp32 } */
+/* { dg-options "-O2 -mtune=i486" } */
+
+extern void abort (void);
+
+struct a
+{
+        int a;
+        char b,c,d,e;
+};
+
+__attribute__ ((noinline))
+__attribute__ ((regparm(1))) t(struct a a)
+{
+        if (a.a!=1 || a.b!=1 || a.c!=1)
+                        abort();
+}
+
+int main()
+{
+        struct a a;
+        a.c=1;
+        a.a=1;
+        a.b=1;
+        t(a);
+        return 0;
+}
+
diff --git a/gcc/testsuite/gcc.target/i386/20060125-2.c b/gcc/testsuite/gcc.target/i386/20060125-2.c
new file mode 100644
index 0000000..7964ca1
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/20060125-2.c
@@ -0,0 +1,30 @@
+/* PR rtl-optimization/25703 */
+/* { dg-do run { target i?86-*-* x86_64-*-* } } */
+/* { dg-require-effective-target ilp32 } */
+/* { dg-options "-O2 -mtune=pentiumpro" } */
+
+extern void abort (void);
+
+struct a
+{
+        int a;
+        char b,c,d,e;
+};
+
+__attribute__ ((noinline))
+__attribute__ ((regparm(1))) t(struct a a)
+{
+        if (a.a!=1 || a.b!=1 || a.c!=1)
+                        abort();
+}
+
+int main()
+{
+        struct a a;
+        a.c=1;
+        a.a=1;
+        a.b=1;
+        t(a);
+        return 0;
+}
+