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be93997c26
Let getTruncateExpr() short-circuit to zero when the value being truncated is known to have at least as many trailing zeros as the target type. Differential Revision: https://reviews.llvm.org/D93973
49 lines
1.3 KiB
LLVM
49 lines
1.3 KiB
LLVM
; RUN: opt < %s -analyze -enable-new-pm=0 -scalar-evolution | FileCheck %s
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; RUN: opt < %s -disable-output "-passes=print<scalar-evolution>" 2>&1 | FileCheck %s
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; Check that we convert
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; trunc(C * a) -> trunc(C) * trunc(a)
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; if C is a constant.
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; CHECK-LABEL: @trunc_of_mul
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define i8 @trunc_of_mul(i32 %a) {
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%b = mul i32 %a, 100
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; CHECK: %c
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; CHECK-NEXT: --> (100 * (trunc i32 %a to i8))
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%c = trunc i32 %b to i8
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ret i8 %c
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}
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; Check that we convert
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; trunc(C + a) -> trunc(C) + trunc(a)
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; if C is a constant.
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; CHECK-LABEL: @trunc_of_add
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define i8 @trunc_of_add(i32 %a) {
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%b = add i32 %a, 100
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; CHECK: %c
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; CHECK-NEXT: --> (100 + (trunc i32 %a to i8))
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%c = trunc i32 %b to i8
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ret i8 %c
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}
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; Check that we truncate to zero values assumed to have at least as many
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; trailing zeros as the target type.
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; CHECK-LABEL: @trunc_to_assumed_zeros
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define i8 @trunc_to_assumed_zeros(i32* %p) {
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%a = load i32, i32* %p
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%and = and i32 %a, 255
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%cmp = icmp eq i32 %and, 0
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tail call void @llvm.assume(i1 %cmp)
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; CHECK: %c
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; CHECK-NEXT: --> 0
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%c = trunc i32 %a to i8
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; CHECK: %d
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; CHECK-NEXT: --> false
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%d = trunc i32 %a to i1
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; CHECK: %e
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; CHECK-NEXT: --> (trunc i32 %a to i16)
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%e = trunc i32 %a to i16
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ret i8 %c
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}
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declare void @llvm.assume(i1 noundef) nofree nosync nounwind willreturn
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