From: Segher Boessenkool <segher@kernel.crashing.org>
To: gcc-patches@gcc.gnu.org
Cc: dje.gcc@gmail.com, Segher Boessenkool <segher@kernel.crashing.org>
Subject: [PATCH 1/2] simplify-rtx: Simplify trunc of and of shiftrt
Date: Mon, 09 Nov 2015 07:33:00 -0000 [thread overview]
Message-ID: <1d3e9ff999e20e4eb13a5825ac084074bd05a397.1447053652.git.segher@kernel.crashing.org> (raw)
If we have
(truncate:M1 (and:M2 (lshiftrt:M2 (x:M2) C) C2))
we can write it instead as
(and:M1 (lshiftrt:M1 (truncate:M1 (x:M2)) C) C2)
(if that is valid, of course), which has smaller modes for the
binary ops, and the truncate can often simplify further (if "x"
is a register, for example).
This fixes gcc.target/powerpc/20050603-3.c for -m32 -mpowerpc64;
also that test is currently restricted to ilp32, but we can run
it with lp64 just fine, in which case it fixes that, too.
Bootstrapped and tested on powerpc64-linux (-m32,-m32/-mpowerpc64,-m64).
Is this okay for trunk?
Segher
2015-11-09 Segher Boessenkool <segher@kernel.crashing.org>
* gcc/simplify-rtx.c (simplify_truncation): Simplify TRUNCATE
of AND of [LA]SHIFTRT.
---
gcc/simplify-rtx.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index 17568ba..1adb393 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -714,6 +714,31 @@ simplify_truncation (machine_mode mode, rtx op,
return simplify_gen_binary (ASHIFT, mode,
XEXP (XEXP (op, 0), 0), XEXP (op, 1));
+ /* Likewise (truncate:QI (and:SI (lshiftrt:SI (x:SI) C) C2)) into
+ (and:QI (lshiftrt:QI (truncate:QI (x:SI)) C) C2) for suitable C
+ and C2. */
+ if (GET_CODE (op) == AND
+ && (GET_CODE (XEXP (op, 0)) == LSHIFTRT
+ || GET_CODE (XEXP (op, 0)) == ASHIFTRT)
+ && CONST_INT_P (XEXP (XEXP (op, 0), 1))
+ && CONST_INT_P (XEXP (op, 1))
+ && UINTVAL (XEXP (XEXP (op, 0), 1)) < precision
+ && ((GET_MODE_MASK (mode) >> UINTVAL (XEXP (XEXP (op, 0), 1)))
+ & UINTVAL (XEXP (op, 1)))
+ == ((GET_MODE_MASK (op_mode) >> UINTVAL (XEXP (XEXP (op, 0), 1)))
+ & UINTVAL (XEXP (op, 1))))
+ {
+ rtx op0 = simplify_gen_unary (TRUNCATE, mode, XEXP (XEXP (op, 0), 0),
+ op_mode);
+ if (op0)
+ {
+ op0 = simplify_gen_binary (LSHIFTRT, mode, op0,
+ XEXP (XEXP (op, 0), 1));
+ if (op0)
+ return simplify_gen_binary (AND, mode, op0, XEXP (op, 1));
+ }
+ }
+
/* Recognize a word extraction from a multi-word subreg. */
if ((GET_CODE (op) == LSHIFTRT
|| GET_CODE (op) == ASHIFTRT)
--
1.9.3
next reply other threads:[~2015-11-09 7:33 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-09 7:33 Segher Boessenkool [this message]
2015-11-09 7:33 ` [PATCH 2/2] rs6000: Extend 20050603-3.c testcase to 64-bit Segher Boessenkool
2015-11-09 16:22 ` David Edelsohn
2015-11-10 11:16 ` [PATCH 1/2] simplify-rtx: Simplify trunc of and of shiftrt Bernd Schmidt
2015-11-10 17:44 ` Segher Boessenkool
2015-11-10 21:04 ` Bernd Schmidt
2015-11-11 14:15 ` Segher Boessenkool
2015-11-13 10:03 Uros Bizjak
2015-11-13 14:36 ` Segher Boessenkool
2015-11-13 15:57 ` Uros Bizjak
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