On Wed, 2020-01-29 at 19:18 +0000, Richard Sandiford wrote:
> Andreas Schwab <sch...@suse.de> writes:
> > On Jan 27 2020, Richard Sandiford wrote:
> >
> > > * simplify-rtx.c (simplify_truncation): Extend sign/zero_extract
> > > simplification to handle subregs as well as bare regs.
> >
> > That breaks gcc.target/m68k/pr39726.c
>
> Gah. Jeff pointed out off-list that it also broke
> gcc.target/sh/pr64345-1.c on sh3-linux-gnu. It didn't look like either
> of them would be fixable in an acceptably non-invasive and unhacky way,
> so I've reverted the patch "for now".
I would have considered letting those two targets regress those tests
to move forward on 87763. aarch64 is (IMHO) more important than the sh
and m68k combined ;-) It also seems to me that your patch generates
better RTL and that we could claim that a port that regresses on code
quality needs its port maintainer to step in and fix the port.
WRT the m68k issue I'd think it could be fixed by twiddling
cbranchsi4_btst_reg_insn_1 to accept a mode iterator on the
zero_extract and making some minor adjustments in its output code.
Something like the attached. I haven't tested it in any real way and
haven't really thought about whether or not it does the right thing for
a MEM operand.
I'd be surprised if the SH fix wasn't similar, but I know almost
nothing about the SH implementation.
Jeff
diff --git a/gcc/config/m68k/m68k.md b/gcc/config/m68k/m68k.md
index 8e35357ea23..78c4cbe4753 100644
--- a/gcc/config/m68k/m68k.md
+++ b/gcc/config/m68k/m68k.md
@@ -644,12 +644,12 @@
return m68k_output_branch_integer (code);
})
-(define_insn "cbranchsi4_btst_reg_insn_1"
+(define_insn "cbranch<mode>4_btst_reg_insn_1"
[(set (pc)
(if_then_else (match_operator 0 "equality_comparison_operator"
- [(zero_extract:SI (match_operand:SI 1 "nonimmediate_operand" "do,dQ")
- (const_int 1)
- (match_operand:SI 2 "const_int_operand" "n,n"))
+ [(zero_extract:I (match_operand:I 1 "nonimmediate_operand" "do,dQ")
+ (const_int 1)
+ (match_operand:I 2 "const_int_operand" "n,n"))
(const_int 0)])
(label_ref (match_operand 3 ""))
(pc)))]
@@ -665,8 +665,9 @@
}
else
{
- operands[2] = GEN_INT (31 - INTVAL (operands[2]));
- code = m68k_output_btst (operands[2], operands[1], code, 31);
+ operands[2] = GEN_INT (GET_MODE_BITSIZE (GET_MODE (operands[1]))
+ - INTVAL (operands[2]) - 1);
+ code = m68k_output_btst (operands[2], operands[1], code, GET_MODE_BITSIZE (GET_MODE (operands[1])) - 1);
}
return m68k_output_branch_integer (code);
}
