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2011-04-26 Chung-Lin Tang <cltang@codesourcery.com>
Backport from mainline:
2011-03-21 Chung-Lin Tang <cltang@codesourcery.com>
gcc/
* simplify-rtx.c (simplify_binary_operation_1): Handle
(xor (and A B) C) case when B and C are both constants.
gcc/testsuite/
* gcc.target/arm/xor-and.c: New.
2011-03-18 Chung-Lin Tang <cltang@codesourcery.com>
gcc/
* combine.c (try_combine): Do simplification only call of
subst() on i2 even when i1 is present. Update comments.
gcc/testsuite/
* gcc.target/arm/unsigned-extend-1.c: New.
=== modified file 'gcc/combine.c'
--- old/gcc/combine.c 2011-01-06 11:02:44 +0000
+++ new/gcc/combine.c 2011-04-14 13:58:12 +0000
@@ -2939,7 +2939,7 @@
/* It is possible that the source of I2 or I1 may be performing
an unneeded operation, such as a ZERO_EXTEND of something
that is known to have the high part zero. Handle that case
- by letting subst look at the innermost one of them.
+ by letting subst look at the inner insns.
Another way to do this would be to have a function that tries
to simplify a single insn instead of merging two or more
@@ -2964,11 +2964,9 @@
subst_low_luid = DF_INSN_LUID (i1);
i1src = subst (i1src, pc_rtx, pc_rtx, 0, 0, 0);
}
- else
- {
- subst_low_luid = DF_INSN_LUID (i2);
- i2src = subst (i2src, pc_rtx, pc_rtx, 0, 0, 0);
- }
+
+ subst_low_luid = DF_INSN_LUID (i2);
+ i2src = subst (i2src, pc_rtx, pc_rtx, 0, 0, 0);
}
n_occurrences = 0; /* `subst' counts here */
=== modified file 'gcc/simplify-rtx.c'
--- old/gcc/simplify-rtx.c 2010-06-25 20:11:56 +0000
+++ new/gcc/simplify-rtx.c 2011-04-14 13:58:12 +0000
@@ -2413,6 +2413,46 @@
XEXP (op0, 1), mode),
op1);
+ /* Given (xor (and A B) C), using P^Q == (~P&Q) | (~Q&P),
+ we can transform like this:
+ (A&B)^C == ~(A&B)&C | ~C&(A&B)
+ == (~A|~B)&C | ~C&(A&B) * DeMorgan's Law
+ == ~A&C | ~B&C | A&(~C&B) * Distribute and re-order
+ Attempt a few simplifications when B and C are both constants. */
+ if (GET_CODE (op0) == AND
+ && CONST_INT_P (op1)
+ && CONST_INT_P (XEXP (op0, 1)))
+ {
+ rtx a = XEXP (op0, 0);
+ rtx b = XEXP (op0, 1);
+ rtx c = op1;
+ HOST_WIDE_INT bval = INTVAL (b);
+ HOST_WIDE_INT cval = INTVAL (c);
+
+ rtx na_c
+ = simplify_binary_operation (AND, mode,
+ simplify_gen_unary (NOT, mode, a, mode),
+ c);
+ if ((~cval & bval) == 0)
+ {
+ /* Try to simplify ~A&C | ~B&C. */
+ if (na_c != NULL_RTX)
+ return simplify_gen_binary (IOR, mode, na_c,
+ GEN_INT (~bval & cval));
+ }
+ else
+ {
+ /* If ~A&C is zero, simplify A&(~C&B) | ~B&C. */
+ if (na_c == const0_rtx)
+ {
+ rtx a_nc_b = simplify_gen_binary (AND, mode, a,
+ GEN_INT (~cval & bval));
+ return simplify_gen_binary (IOR, mode, a_nc_b,
+ GEN_INT (~bval & cval));
+ }
+ }
+ }
+
/* (xor (comparison foo bar) (const_int 1)) can become the reversed
comparison if STORE_FLAG_VALUE is 1. */
if (STORE_FLAG_VALUE == 1
=== added file 'gcc/testsuite/gcc.target/arm/unsigned-extend-1.c'
--- old/gcc/testsuite/gcc.target/arm/unsigned-extend-1.c 1970-01-01 00:00:00 +0000
+++ new/gcc/testsuite/gcc.target/arm/unsigned-extend-1.c 2011-04-14 13:58:12 +0000
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=armv6" } */
+
+unsigned char foo (unsigned char c)
+{
+ return (c >= '0') && (c <= '9');
+}
+
+/* { dg-final { scan-assembler-not "uxtb" } } */
=== added file 'gcc/testsuite/gcc.target/arm/xor-and.c'
--- old/gcc/testsuite/gcc.target/arm/xor-and.c 1970-01-01 00:00:00 +0000
+++ new/gcc/testsuite/gcc.target/arm/xor-and.c 2011-04-14 13:58:12 +0000
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O -march=armv6" } */
+
+unsigned short foo (unsigned short x)
+{
+ x ^= 0x4002;
+ x >>= 1;
+ x |= 0x8000;
+ return x;
+}
+
+/* { dg-final { scan-assembler "orr" } } */
+/* { dg-final { scan-assembler-not "mvn" } } */
+/* { dg-final { scan-assembler-not "uxth" } } */
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