This is a revamp of what started as a target specific patch.
Basically xalan (corrected, I originally thought it was perlbench) has a
bitset implementation with a bit of an oddity. Specifically setBit will
clear the bit before it is set:
if (bitToSet < 32)
{
fBits1 &= ~mask;
fBits1 |= mask;
}
else
{
fBits2 &= ~mask;
fBits2 |= mask;
}
We can clean this up pretty easily in RTL with a small bit of code in
simplify-rtx. While xalan doesn't have other cases, we can synthesize
tests pretty easily and handle them as well.
It turns out we don't actually have to recognize this stuff at the bit
level, just standard logical identities are sufficient. For example
(X | Y) & ~Y -> X & ~Y
Andrew P. might poke at this at the gimple level. The type changes
kindof get in the way in gimple but he's much better at match.pd than I
am, so if he wants to chase it from the gimple side, I'll fully support
that.
Bootstrapped and regression tested on x86. Also run through my tester
on its embedded targets.
Pushing to the trunk.
jeff
commit 05daf617ea22e1d818295ed2d037456937e23530
Author: Jeff Law
Date: Sat May 25 12:39:05 2024 -0600
[committed] [v2] More logical op simplifications in simplify-rtx.cc
This is a revamp of what started as a target specific patch.
Basically xalan (corrected, I originally thought it was perlbench) has a
bitset
implementation with a bit of an oddity. Specifically setBit will clear the
bit
before it is set:
> if (bitToSet < 32)
> {
> fBits1 &= ~mask;
> fBits1 |= mask;
> }
> else
> {
> fBits2 &= ~mask;
> fBits2 |= mask;
> }
We can clean this up pretty easily in RTL with a small bit of code in
simplify-rtx. While xalan doesn't have other cases, we can synthesize tests
pretty easily and handle them as well.
It turns out we don't actually have to recognize this stuff at the bit
level,
just standard logical identities are sufficient. For example
(X | Y) & ~Y -> X & ~Y
Andrew P. might poke at this at the gimple level. The type changes kindof
get
in the way in gimple but he's much better at match.pd than I am, so if he
wants
to chase it from the gimple side, I'll fully support that.
Bootstrapped and regression tested on x86. Also run through my tester on
its
embedded targets.
Pushing to the trunk.
gcc/
* simplify-rtx.cc (simplify_context::simplify_binary_operation_1):
Handle
more logical simplifications.
gcc/testsuite/
* g++.target/riscv/redundant-bitmap-1.C: New test.
* g++.target/riscv/redundant-bitmap-2.C: New test.
* g++.target/riscv/redundant-bitmap-3.C: New test.
* g++.target/riscv/redundant-bitmap-4.C: New test.
diff --git a/gcc/simplify-rtx.cc b/gcc/simplify-rtx.cc
index 53f54d1d392..5caf1dfd957 100644
--- a/gcc/simplify-rtx.cc
+++ b/gcc/simplify-rtx.cc
@@ -3549,6 +3549,12 @@ simplify_context::simplify_binary_operation_1 (rtx_code
code,
return tem;
}
+ /* Convert (ior (and (not A) B) A) into A | B. */
+ if (GET_CODE (op0) == AND
+ && GET_CODE (XEXP (op0, 0)) == NOT
+ && rtx_equal_p (XEXP (XEXP (op0, 0), 0), op1))
+ return simplify_gen_binary (IOR, mode, XEXP (op0, 1), op1);
+
tem = simplify_byte_swapping_operation (code, mode, op0, op1);
if (tem)
return tem;
@@ -3801,6 +3807,12 @@ simplify_context::simplify_binary_operation_1 (rtx_code
code,
return tem;
}
+ /* Convert (xor (and (not A) B) A) into A | B. */
+ if (GET_CODE (op0) == AND
+ && GET_CODE (XEXP (op0, 0)) == NOT
+ && rtx_equal_p (XEXP (XEXP (op0, 0), 0), op1))
+ return simplify_gen_binary (IOR, mode, XEXP (op0, 1), op1);
+
tem = simplify_byte_swapping_operation (code, mode, op0, op1);
if (tem)
return tem;
@@ -4006,6 +4018,23 @@ simplify_context::simplify_binary_operation_1 (rtx_code
code,
&& rtx_equal_p (op1, XEXP (XEXP (op0, 1), 0)))
return simplify_gen_binary (AND, mode, op1, XEXP (op0, 0));
+ /* (and (ior/xor (X Y) (not Y)) -> X & ~Y */
+ if ((GET_CODE (op0) == IOR || GET_CODE (op0) == XOR)
+ && GET_CODE (op1) == NOT
+ && rtx_equal_p (XEXP (op1, 0), XEXP (op0, 1)))
+ return simplify_gen_binary (AND, mode, XEXP (op0, 0),
+ simplify_gen_unary (NOT, mode,
+
