[PATCH] D145334: [InstCombine] Add tests for transform `(shift X, (Or Y, BitWidth-1))`; NFC

[Noah Goldstein via Phabricator via llvm-commits]

goldstein.w.n created this revision.
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Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D145334

Files:
  llvm/test/Transforms/InstCombine/shift.ll


Index: llvm/test/Transforms/InstCombine/shift.ll
===================================================================
--- llvm/test/Transforms/InstCombine/shift.ll
+++ llvm/test/Transforms/InstCombine/shift.ll
@@ -2067,3 +2067,51 @@
   %shl = shl i32 2, %tz
   ret i32 %shl
 }
+
+; shift (X, amt | bitwidth - 1) -> shift (X, bitwidth - 1)
+define i6 @shl_or7_eq_shl7(i6 %x, i6 %c) {
+; CHECK-LABEL: @shl_or7_eq_shl7(
+; CHECK-NEXT:    [[AMT:%.*]] = or i6 [[C:%.*]], 5
+; CHECK-NEXT:    [[Y:%.*]] = shl nsw i6 [[X:%.*]], [[AMT]]
+; CHECK-NEXT:    ret i6 [[Y]]
+;
+  %amt = or i6 %c, 5
+  ;; nsw not needed for transform, just check that we propegate.
+  %y = shl nsw i6 %x, %amt
+  ret i6 %y
+}
+
+define <2 x i8> @lshr_vec_or7_eq_shl7(<2 x i8> %x, <2 x i8> %c) {
+; CHECK-LABEL: @lshr_vec_or7_eq_shl7(
+; CHECK-NEXT:    [[AMT:%.*]] = or <2 x i8> [[C:%.*]], <i8 7, i8 7>
+; CHECK-NEXT:    [[Y:%.*]] = lshr exact <2 x i8> [[X:%.*]], [[AMT]]
+; CHECK-NEXT:    ret <2 x i8> [[Y]]
+;
+  %amt = or <2 x i8> %c, <i8 7, i8 7>
+  ;; exact not needed for transform, just check that we propegate.
+  %y = lshr exact <2 x i8> %x, %amt
+  ret <2 x i8> %y
+}
+
+define <2 x i8> @ashr_vec_or7_eq_ashr7(<2 x i8> %x, <2 x i8> %c) {
+; CHECK-LABEL: @ashr_vec_or7_eq_ashr7(
+; CHECK-NEXT:    [[AMT:%.*]] = or <2 x i8> [[C:%.*]], <i8 7, i8 7>
+; CHECK-NEXT:    [[Y:%.*]] = ashr <2 x i8> [[X:%.*]], [[AMT]]
+; CHECK-NEXT:    ret <2 x i8> [[Y]]
+;
+  %amt = or <2 x i8> %c, <i8 7, i8 7>
+  %y = ashr <2 x i8> %x, %amt
+  ret <2 x i8> %y
+}
+
+; Negative test not bitwidth - 1
+define <2 x i8> @ashr_vec_or6_fail(<2 x i8> %x, <2 x i8> %c) {
+; CHECK-LABEL: @ashr_vec_or6_fail(
+; CHECK-NEXT:    [[AMT:%.*]] = or <2 x i8> [[C:%.*]], <i8 6, i8 6>
+; CHECK-NEXT:    [[Y:%.*]] = ashr <2 x i8> [[X:%.*]], [[AMT]]
+; CHECK-NEXT:    ret <2 x i8> [[Y]]
+;
+  %amt = or <2 x i8> %c, <i8 6, i8 6>
+  %y = ashr <2 x i8> %x, %amt
+  ret <2 x i8> %y
+}


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