On Tue, 2025-01-21 at 22:14 +0800, Xi Ruoyao wrote:
> On Tue, 2025-01-21 at 21:52 +0800, Xi Ruoyao wrote:
> > > struct Pair { unsigned long a, b; };
> > >
> > > struct Pair
> > > test (struct Pair p, long x, long y)
> > > {
> > > p.a &= 0xffffffff;
> > > p.a <<= 2;
> > > p.a += x;
> > > p.b &= 0xffffffff;
> > > p.b <<= 2;
> > > p.b += x;
> > > return p;
> > > }
> > >
> > > in GCC 13 the result is:
> > >
> > > or $r12,$r4,$r0
> >
> > Hmm, this strange move is caused by "&" in bstrpick_alsl_paired. Is it
> > really needed for the fusion?
>
> Never mind, it's needed or a = ((a & 0xffffffff) << 1) + a will blow up.
> Stupid I.
>
> > > bstrpick.d $r4,$r12,31,0
> > > alsl.d $r4,$r4,$r6,2
> > > or $r12,$r5,$r0
> > > bstrpick.d $r5,$r12,31,0
> > > alsl.d $r5,$r5,$r6,2
> > > jr $r1
This fixes the test case and forces to emit alsl.d for (a & 0xffffffff)
<< [1234]:
diff --git a/gcc/config/loongarch/loongarch.md
b/gcc/config/loongarch/loongarch.md
index 10197b9d9d5..7b5b77c56ac 100644
--- a/gcc/config/loongarch/loongarch.md
+++ b/gcc/config/loongarch/loongarch.md
@@ -3134,8 +3134,50 @@ (define_insn_and_split "<optab>_shift_reverse<X:mode>"
<MODE>mode)"
"#"
"&& true"
+ [(set (match_dup 0) (ashift:X (match_dup 0) (match_dup 2)))]
+ {
+ operands[3] = loongarch_reassoc_shift_bitwise (<is_and>,
+ operands[2],
+ operands[3],
+ <MODE>mode);
+
+ if (ins_zero_bitmask_operand (operands[3], <MODE>mode))
+ {
+ gcc_checking_assert (<is_and>);
+ emit_move_insn (operands[0], operands[1]);
+ operands[1] = operands[0];
+ }
+
+ emit_insn (gen_<optab><mode>3 (operands[0], operands[1], operands[3]));
+
+ if (<is_and>
+ && TARGET_64BIT
+ && si_mask_operand (operands[3], DImode)
+ && const_immalsl_operand (operands[2], SImode))
+ {
+ /* Special case for bstrpick.d + alsl.d fusion
+ TODO: TARGET_SCHED_MACRO_FUSION_PAIR_P */
+ emit_insn (gen_alsldi3 (operands[0], operands[0],
+ operands[2], gen_rtx_REG (DImode, 0)));
+ DONE;
+ }
+ })
+
+(define_insn_and_split "<optab>_alsl_reverse<X:mode>"
+ [(set (match_operand:X 0 "register_operand" "=r")
+ (plus:X
+ (any_bitwise:X
+ (ashift:X (match_operand:X 1 "register_operand" "r")
+ (match_operand:SI 2 "const_immalsl_operand" "i"))
+ (match_operand:X 3 "const_int_operand" "i"))
+ (match_operand:X 4 "register_operand" "r")))]
+ "loongarch_reassoc_shift_bitwise (<is_and>, operands[2], operands[3],
+ <MODE>mode)"
+ "#"
+ "&& true"
[(set (match_dup 0) (any_bitwise:X (match_dup 1) (match_dup 3)))
- (set (match_dup 0) (ashift:X (match_dup 0) (match_dup 2)))]
+ (set (match_dup 0) (plus:X (ashift:X (match_dup 0) (match_dup 2))
+ (match_dup 4)))]
{
operands[3] = loongarch_reassoc_shift_bitwise (<is_and>,
operands[2],
I guess it'll work combined with TARGET_SCHED_MACRO_FUSION_PAIR_P
implemented.
--
Xi Ruoyao <[email protected]>
School of Aerospace Science and Technology, Xidian University
