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1b7f7179a4
Multiply and shl have different signed overflow behavior in some cases. But it looks like we should be ok as long as the shift amount is less than bitwidth - 1. Alive2: http://volta.cs.utah.edu:8080/z/MM4WZP Differential Revision: https://reviews.llvm.org/D81189
89 lines
2.2 KiB
LLVM
89 lines
2.2 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -reassociate -dce -S | FileCheck %s
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; PR12985
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; Verify the nsw flags are preserved when converting shl to mul.
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define i32 @shl_to_mul_nsw(i32 %i) {
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;
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; CHECK-LABEL: @shl_to_mul_nsw(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[MUL:%.*]] = mul i32 [[I:%.*]], -2147483648
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; CHECK-NEXT: [[MUL2:%.*]] = add i32 [[MUL]], 1
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; CHECK-NEXT: ret i32 [[MUL2]]
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;
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entry:
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%mul = shl nsw i32 %i, 31
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%mul2 = add i32 %mul, 1
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ret i32 %mul2
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}
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define i32 @shl_to_mul_nsw_2(i32 %i) {
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;
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; CHECK-LABEL: @shl_to_mul_nsw_2(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[MUL:%.*]] = mul nsw i32 [[I:%.*]], 1073741824
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; CHECK-NEXT: [[MUL2:%.*]] = add i32 [[MUL]], 1
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; CHECK-NEXT: ret i32 [[MUL2]]
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;
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entry:
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%mul = shl nsw i32 %i, 30
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%mul2 = add i32 %mul, 1
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ret i32 %mul2
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}
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define i32 @shl_to_mul_nuw(i32 %i) {
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;
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; CHECK-LABEL: @shl_to_mul_nuw(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[MUL:%.*]] = mul nuw i32 [[I:%.*]], 4
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; CHECK-NEXT: [[MUL2:%.*]] = add i32 [[MUL]], 1
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; CHECK-NEXT: ret i32 [[MUL2]]
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;
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entry:
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%mul = shl nuw i32 %i, 2
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%mul2 = add i32 %mul, 1
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ret i32 %mul2
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}
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define i32 @shl_to_mul_nuw_nsw(i32 %i) {
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;
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; CHECK-LABEL: @shl_to_mul_nuw_nsw(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[MUL:%.*]] = mul nuw nsw i32 [[I:%.*]], 4
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; CHECK-NEXT: [[MUL2:%.*]] = add i32 [[MUL]], 1
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; CHECK-NEXT: ret i32 [[MUL2]]
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;
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entry:
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%mul = shl nuw nsw i32 %i, 2
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%mul2 = add i32 %mul, 1
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ret i32 %mul2
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}
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define i32 @shl_to_mul_nuw_nsw_bitwidth_m1(i32 %i) {
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;
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; CHECK-LABEL: @shl_to_mul_nuw_nsw_bitwidth_m1(
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; CHECK-NEXT: entry:
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; CHECK-NEXT: [[MUL:%.*]] = mul nuw nsw i32 [[I:%.*]], -2147483648
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; CHECK-NEXT: [[MUL2:%.*]] = add i32 [[MUL]], 1
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; CHECK-NEXT: ret i32 [[MUL2]]
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;
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entry:
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%mul = shl nuw nsw i32 %i, 31
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%mul2 = add i32 %mul, 1
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ret i32 %mul2
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}
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define i2 @pr23926(i2 %X1, i2 %X2) {
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;
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; CHECK-LABEL: @pr23926(
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; CHECK-NEXT: [[X1_NEG:%.*]] = sub i2 0, [[X1:%.*]]
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; CHECK-NEXT: [[ADD_NEG:%.*]] = add i2 [[X1_NEG]], -1
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; CHECK-NEXT: [[SUB:%.*]] = add i2 [[ADD_NEG]], [[X2:%.*]]
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; CHECK-NEXT: ret i2 [[SUB]]
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;
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%add = add nuw i2 %X1, 1
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%sub = sub nuw nsw i2 %X2, %add
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ret i2 %sub
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}
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