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[PATCH][simplify-rtx][2/2] Use constants from pool when simplifying binops
- From: Kyrill Tkachov <kyrylo dot tkachov at arm dot com>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Cc: Eric Botcazou <ebotcazou at adacore dot com>, Segher Boessenkool <segher at kernel dot crashing dot org>
- Date: Mon, 19 Oct 2015 14:57:54 +0100
- Subject: [PATCH][simplify-rtx][2/2] Use constants from pool when simplifying binops
- Authentication-results: sourceware.org; auth=none
Hi all,
This second patch teaches simplify_binary_operation to return the dereferenced
constants from the constant pool in the binary expression if other simplifications failed.
This, combined with the 1/2 patch for aarch64
(https://gcc.gnu.org/ml/gcc-patches/2015-10/msg01744.html) allow for:
int
foo (float a)
{
return a * 32.0f;
}
to generate the code:
foo:
fcvtzs w0, s0, #5
ret
because combine now successfully tries to match:
(set (reg/i:SI 0 x0)
(fix:SI (mult:SF (reg:SF 32 v0 [ a ])
(const_double:SF 3.2e+1 [0x0.8p+6]))))
whereas before it would not try the to use the const_double directly
but rather its constant pool reference.
I've seen this patch trigger once in 453.gromacs from SPEC2006 on aarch64 where it
ended up eliminating a floating-point multiplication and a load from a constant pool.
There were no other changes, so I reckon this is pretty low impact.
Bootstrapped and tested on aarch64, arm, x86_64.
CC'ing Eric as this is an RTL optimisation and Segher as this is something that
has an effect through combine.
Ok for trunk?
Thanks,
Kyrill
2015-10-19 Kyrylo Tkachov <kyrylo.tkachov@arm.com>
* simplify-rtx.c (simplify_binary_operation): If either operand was
a constant pool reference use them if all other simplifications failed.
2015-10-19 Kyrylo Tkachov <kyrylo.tkachov@arm.com>
* gcc.target/aarch64/fmul_fcvt_1.c: Add multiply-by-32 cases.
commit f941a03f6ca5dcc0d509490d0e0ec39cefed714b
Author: Kyrylo Tkachov <kyrylo.tkachov@arm.com>
Date: Mon Oct 12 17:12:34 2015 +0100
[simplify-rtx] Use constants from pool when simplifying binops
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index 5ea5522..519850a 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -2001,7 +2001,17 @@ simplify_binary_operation (enum rtx_code code, machine_mode mode,
tem = simplify_const_binary_operation (code, mode, trueop0, trueop1);
if (tem)
return tem;
- return simplify_binary_operation_1 (code, mode, op0, op1, trueop0, trueop1);
+ tem = simplify_binary_operation_1 (code, mode, op0, op1, trueop0, trueop1);
+
+ if (tem)
+ return tem;
+
+ /* If the above steps did not result in a simplification and op0 or op1
+ were constant pool references, use the referenced constants directly. */
+ if (trueop0 != op0 || trueop1 != op1)
+ return simplify_gen_binary (code, mode, trueop0, trueop1);
+
+ return NULL_RTX;
}
/* Subroutine of simplify_binary_operation. Simplify a binary operation
diff --git a/gcc/testsuite/gcc.target/aarch64/fmul_fcvt_1.c b/gcc/testsuite/gcc.target/aarch64/fmul_fcvt_1.c
index 5af8290..354f2be 100644
--- a/gcc/testsuite/gcc.target/aarch64/fmul_fcvt_1.c
+++ b/gcc/testsuite/gcc.target/aarch64/fmul_fcvt_1.c
@@ -83,6 +83,17 @@ FUNC_DEFD (16)
/* { dg-final { scan-assembler "fcvtzu\tx\[0-9\], d\[0-9\]*.*#4" } } */
/* { dg-final { scan-assembler "fcvtzu\tw\[0-9\], d\[0-9\]*.*#4" } } */
+FUNC_DEFS (32)
+FUNC_DEFD (32)
+/* { dg-final { scan-assembler "fcvtzs\tw\[0-9\], s\[0-9\]*.*#5" } } */
+/* { dg-final { scan-assembler "fcvtzs\tx\[0-9\], s\[0-9\]*.*#5" } } */
+/* { dg-final { scan-assembler "fcvtzs\tx\[0-9\], d\[0-9\]*.*#5" } } */
+/* { dg-final { scan-assembler "fcvtzs\tw\[0-9\], d\[0-9\]*.*#5" } } */
+/* { dg-final { scan-assembler "fcvtzu\tw\[0-9\], s\[0-9\]*.*#5" } } */
+/* { dg-final { scan-assembler "fcvtzu\tx\[0-9\], s\[0-9\]*.*#5" } } */
+/* { dg-final { scan-assembler "fcvtzu\tx\[0-9\], d\[0-9\]*.*#5" } } */
+/* { dg-final { scan-assembler "fcvtzu\tw\[0-9\], d\[0-9\]*.*#5" } } */
+
#define FUNC_TESTS(__a, __b) \
do \
@@ -120,10 +131,12 @@ main (void)
FUNC_TESTS (4, i);
FUNC_TESTS (8, i);
FUNC_TESTS (16, i);
+ FUNC_TESTS (32, i);
FUNC_TESTD (4, i);
FUNC_TESTD (8, i);
FUNC_TESTD (16, i);
+ FUNC_TESTD (32, i);
}
return 0;
}