================
@@ -294,4 +294,13 @@ def : Pat<(f32 fpnegimm0), (FNEGS (FZEROS))>;
// VIS3 instruction patterns.
let Predicates = [HasVIS3] in {
def : Pat<(i64 (adde i64:$lhs, i64:$rhs)), (ADDXCCC $lhs, $rhs)>;
+
+def : Pat<(i64 (mulhu i64:$lhs, i64:$rhs)), (UMULXHI $lhs, $rhs)>;
+// Signed "MULXHI".
+// Based on the formula presented in OSA2011 ยง7.140, but with bitops to select
+// the values to be added.
+def : Pat<(i64 (mulhs i64:$lhs, i64:$rhs)),
+ (SUBrr (UMULXHI $lhs, $rhs),
+ (ADDrr (ANDrr (SRAXri $lhs, 63), $rhs),
+ (ANDrr (SRAXri $rhs, 63), $lhs)))>;
----------------
koachan wrote:
It works, in that it cuts down on the number of multiplies, but it still seems
to produce more instructions than manual matching (e.g in
`signed_multiply_extend`):
```
; VIS3-LABEL: signed_multiply_extend:
; VIS3: ! %bb.0:
; VIS3-NEXT: srax %o0, 63, %o2
; VIS3-NEXT: srax %o1, 63, %o3
; VIS3-NEXT: umulxhi %o1, %o0, %o4
; VIS3-NEXT: sub %g0, %o1, %o5
; VIS3-NEXT: and %o2, %o5, %o2
; VIS3-NEXT: add %o4, %o2, %o2
; VIS3-NEXT: sub %g0, %o0, %o4
; VIS3-NEXT: and %o3, %o4, %o3
; VIS3-NEXT: add %o2, %o3, %o2
; VIS3-NEXT: mulx %o1, %o0, %o1
; VIS3-NEXT: retl
; VIS3-NEXT: mov %o2, %o0
```
https://github.com/llvm/llvm-project/pull/135714
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