2009-10-28 Paolo Bonzini <bonzini@gnu.org>

	PR rtl-optimization/39715
	* combine.c (simplify_comparison): Use extensions to
	widen comparisons.  Try an ANDing first.

testsuite:
2009-10-28  Paolo Bonzini  <bonzini@gnu.org>

	PR rtl-optimization/39715
	* gcc.target/arm/thumb-bitfld1.c: New.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@153651 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 17793bf..db1d1c8 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,11 @@
 2009-10-28  Paolo Bonzini  <bonzini@gnu.org>
 
+       PR rtl-optimization/39715
+       * combine.c (simplify_comparison): Use extensions to
+       widen comparisons.  Try an ANDing first.
+
+2009-10-28  Paolo Bonzini  <bonzini@gnu.org>
+
        PR rtl-optimization/40741
        * config/arm/arm.c (thumb1_rtx_costs): IOR or XOR with
        a small constant is cheap.

diff --git a/gcc/combine.c b/gcc/combine.c
index 2311755..80c538e 100644 (file)
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -11467,6 +11467,22 @@ simplify_comparison (enum rtx_code code, rtx *pop0, rtx *pop1)
        {
          int zero_extended;
 
+         /* If this is a test for negative, we can make an explicit
+            test of the sign bit.  Test this first so we can use
+            a paradoxical subreg to extend OP0.  */
+
+         if (op1 == const0_rtx && (code == LT || code == GE)
+             && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT)
+           {
+             op0 = simplify_gen_binary (AND, tmode,
+                                        gen_lowpart (tmode, op0),
+                                        GEN_INT ((HOST_WIDE_INT) 1
+                                                 << (GET_MODE_BITSIZE (mode)
+                                                     - 1)));
+             code = (code == LT) ? NE : EQ;
+             break;
+           }
+
          /* If the only nonzero bits in OP0 and OP1 are those in the
             narrower mode and this is an equality or unsigned comparison,
             we can use the wider mode.  Similarly for sign-extended
@@ -11497,27 +11513,20 @@ simplify_comparison (enum rtx_code code, rtx *pop0, rtx *pop1)
                                                        XEXP (op0, 0)),
                                           gen_lowpart (tmode,
                                                        XEXP (op0, 1)));
-
-             op0 = gen_lowpart (tmode, op0);
-             if (zero_extended && CONST_INT_P (op1))
-               op1 = GEN_INT (INTVAL (op1) & GET_MODE_MASK (mode));
-             op1 = gen_lowpart (tmode, op1);
-             break;
-           }
-
-         /* If this is a test for negative, we can make an explicit
-            test of the sign bit.  */
-
-         if (op1 == const0_rtx && (code == LT || code == GE)
-             && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT)
-           {
-             op0 = simplify_gen_binary (AND, tmode,
-                                        gen_lowpart (tmode, op0),
-                                        GEN_INT ((HOST_WIDE_INT) 1
-                                                 << (GET_MODE_BITSIZE (mode)
-                                                     - 1)));
-             code = (code == LT) ? NE : EQ;
-             break;
+             else
+               {
+                 if (zero_extended)
+                   {
+                     op0 = simplify_gen_unary (ZERO_EXTEND, tmode, op0, mode);
+                     op1 = simplify_gen_unary (ZERO_EXTEND, tmode, op1, mode);
+                   }
+                 else
+                   {
+                     op0 = simplify_gen_unary (SIGN_EXTEND, tmode, op0, mode);
+                     op1 = simplify_gen_unary (SIGN_EXTEND, tmode, op1, mode);
+                   }
+                 break;
+               }
            }
        }
 

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index aa64dab..1d59b71 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,10 @@
 2009-10-28  Paolo Bonzini  <bonzini@gnu.org>
 
+       PR rtl-optimization/39715
+       * gcc.target/arm/thumb-bitfld1.c: New.
+
+2009-10-28  Paolo Bonzini  <bonzini@gnu.org>
+
        PR rtl-optimization/40741
        * gcc.target/arm/thumb-branch1.c: New.
 

diff --git a/gcc/testsuite/gcc.target/arm/thumb-bitfld1.c b/gcc/testsuite/gcc.target/arm/thumb-bitfld1.c
new file mode 100644 (file)
index 0000000..7741b4f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/thumb-bitfld1.c
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -mthumb -march=armv5t" }  */
+
+struct foo
+{
+  unsigned b31 : 1;
+  unsigned b30 : 1;
+  unsigned b29 : 1;
+  unsigned b28 : 1;
+  unsigned rest : 28;
+};
+foo(a)
+     struct foo a;
+{
+  return a.b30;
+}
+
+/* { dg-final { scan-assembler-times "lsl" 1 } } */
+/* { dg-final { scan-assembler-times "lsr" 1 } } */