[llvm] Fold SVE mul and mul_u to neg during isel (PR #160828)

[Paul Walker via llvm-commits]

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@@ -1012,6 +1012,36 @@ let Predicates = [HasSVE_or_SME] in {
   defm SEL_ZPZZ   : sve_int_sel_vvv<"sel", vselect>;
 
   defm SPLICE_ZPZ : sve_int_perm_splice<"splice", AArch64splice>;
+
+  // mul x (splat -1) -> neg x
+  def : Pat<(nxv16i8 (AArch64mul_m1 nxv16i1:$Op1, nxv16i8:$Op2, (nxv16i8 (splat_vector (i32 -1))))),
+      (NEG_ZPmZ_B $Op2, $Op1, $Op2)>;
+  def : Pat<(nxv8i16 (AArch64mul_m1 nxv8i1:$Op1, nxv8i16:$Op2, (nxv8i16 (splat_vector (i32 -1))))),
+      (NEG_ZPmZ_H $Op2, $Op1, $Op2)>;
+  def : Pat<(nxv4i32 (AArch64mul_m1 nxv4i1:$Op1, nxv4i32:$Op2, (nxv4i32 (splat_vector (i32 -1))))),
+      (NEG_ZPmZ_S $Op2, $Op1, $Op2)>;
+  def : Pat<(nxv2i64 (AArch64mul_m1 nxv2i1:$Op1, nxv2i64:$Op2, (nxv2i64 (splat_vector (i64 -1))))),
+      (NEG_ZPmZ_D $Op2, $Op1, $Op2)>;
+
+  let AddedComplexity = 5 in {
+    def : Pat<(nxv16i8 (AArch64mul_p nxv16i1:$Op1, nxv16i8:$Op2, (nxv16i8 (splat_vector (i32 -1))))),
+        (NEG_ZPmZ_B_UNDEF $Op2, $Op1, $Op2)>;
+    def : Pat<(nxv8i16 (AArch64mul_p nxv8i1:$Op1, nxv8i16:$Op2, (nxv8i16 (splat_vector (i32 -1))))),
+        (NEG_ZPmZ_H_UNDEF $Op2, $Op1, $Op2)>;
+    def : Pat<(nxv4i32 (AArch64mul_p nxv4i1:$Op1, nxv4i32:$Op2, (nxv4i32 (splat_vector (i32 -1))))),
+        (NEG_ZPmZ_S_UNDEF $Op2, $Op1, $Op2)>;
+    def : Pat<(nxv2i64 (AArch64mul_p nxv2i1:$Op1, nxv2i64:$Op2, (nxv2i64 (splat_vector (i64 -1))))),
+        (NEG_ZPmZ_D_UNDEF $Op2, $Op1, $Op2)>;
+  }
+
+  def : Pat<(nxv16i8 (AArch64mul_m1 nxv16i1:$Op1, (nxv16i8 (splat_vector (i32 -1))), nxv16i8:$Op2)),
+        (NEG_ZPmZ_B (DUP_ZI_B -1, 0) , $Op1, $Op2)>;
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paulwalker-arm wrote:

Rouge whitespace `(DUP_ZI_B -1, 0) ,`. 

https://github.com/llvm/llvm-project/pull/160828