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-rw-r--r--gcc/ChangeLog5
-rw-r--r--gcc/cse.c6
-rw-r--r--gcc/testsuite/ChangeLog5
-rw-r--r--gcc/testsuite/gcc.dg/pr53352.c41
4 files changed, 56 insertions, 1 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 320ae0d09cc..ea1941e17b9 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2012-05-18 Meador Inge <meadori@codesourcery.com>
+
+ PR rtl-optimization/53352
+ * cse.c (equiv_constant): Ignore paradoxical subregs.
+
2012-05-17 Steven Bosscher <steven@gcc.gnu.org>
PR rtl-optimization/53125
diff --git a/gcc/cse.c b/gcc/cse.c
index 0ad7b2e2a46..9f4e97932ed 100644
--- a/gcc/cse.c
+++ b/gcc/cse.c
@@ -3786,8 +3786,12 @@ equiv_constant (rtx x)
}
}
- /* Otherwise see if we already have a constant for the inner REG. */
+ /* Otherwise see if we already have a constant for the inner REG,
+ and if that is enough to calculate an equivalent constant for
+ the subreg. Note that the upper bits of paradoxical subregs
+ are undefined, so they cannot be said to equal anything. */
if (REG_P (SUBREG_REG (x))
+ && GET_MODE_SIZE (mode) <= GET_MODE_SIZE (imode)
&& (new_rtx = equiv_constant (SUBREG_REG (x))) != 0)
return simplify_subreg (mode, new_rtx, imode, SUBREG_BYTE (x));
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 22f2982bbab..64a011c0e87 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2012-05-18 Meador Inge <meadori@codesourcery.com>
+
+ PR rtl-optimization/53352
+ * gcc.dg/pr53352.c: New test.
+
2012-05-17 David S. Miller <davem@davemloft.net>
* gfortran.dg/bessel_7.f90: Bump allowed precision to avoid
diff --git a/gcc/testsuite/gcc.dg/pr53352.c b/gcc/testsuite/gcc.dg/pr53352.c
new file mode 100644
index 00000000000..1d2edf8bb8c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr53352.c
@@ -0,0 +1,41 @@
+/* { dg-do run } */
+/* { dg-options "-O1" } */
+
+#include <stdlib.h>
+
+typedef union
+{
+ struct
+ {
+ unsigned char a;
+ unsigned char b;
+ unsigned char c;
+ unsigned char d;
+ } parts;
+ unsigned long whole;
+} T;
+
+T *g_t;
+
+void bar (unsigned long x)
+{
+ if (x != 0)
+ abort ();
+}
+
+int main ()
+{
+ T one;
+ T two;
+ T tmp1, tmp2;
+
+ one.whole = 0xFFE0E0E0UL;
+ two.whole = 0xFF000000UL;
+ tmp1.parts = two.parts;
+ tmp2.parts = one.parts;
+ tmp2.parts.c = tmp1.parts.c;
+ one.parts = tmp2.parts;
+
+ g_t = &one;
+ bar (0);
+}