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b34960fe47
The motivating case is from PR37549: https://bugs.llvm.org/show_bug.cgi?id=37549 The analysis improvement allows us to form a vector 'select' out of bitwise logic (the use of ComputeNumSignBits was added at rL345149). The smaller test shows another InstCombine improvement - we use ComputeNumSignBits to add 'nsw' to shift-left. But the negative test shows an example where we must not add 'nsw' - when the shuffle mask contains undef elements. Differential Revision: https://reviews.llvm.org/D53659 llvm-svn: 345429
133 lines
3.8 KiB
LLVM
133 lines
3.8 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -instcombine -S | FileCheck %s
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define i32 @sub1(i32 %x) {
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; CHECK-LABEL: @sub1(
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; CHECK-NEXT: [[Y:%.*]] = sub i32 0, [[X:%.*]]
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; CHECK-NEXT: [[Z:%.*]] = sdiv i32 [[Y]], 337
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; CHECK-NEXT: ret i32 [[Z]]
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;
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%y = sub i32 0, %x
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%z = sdiv i32 %y, 337
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ret i32 %z
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}
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define i32 @sub2(i32 %x) {
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; CHECK-LABEL: @sub2(
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; CHECK-NEXT: [[Z:%.*]] = sdiv i32 [[X:%.*]], -337
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; CHECK-NEXT: ret i32 [[Z]]
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;
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%y = sub nsw i32 0, %x
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%z = sdiv i32 %y, 337
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ret i32 %z
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}
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define i1 @shl_icmp(i64 %X) {
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; CHECK-LABEL: @shl_icmp(
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; CHECK-NEXT: [[B:%.*]] = icmp eq i64 [[X:%.*]], 0
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; CHECK-NEXT: ret i1 [[B]]
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;
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%A = shl nuw i64 %X, 2 ; X/4
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%B = icmp eq i64 %A, 0
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ret i1 %B
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}
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define i64 @shl1(i64 %X, i64* %P) {
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; CHECK-LABEL: @shl1(
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; CHECK-NEXT: [[A:%.*]] = and i64 [[X:%.*]], 312
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; CHECK-NEXT: store i64 [[A]], i64* [[P:%.*]], align 4
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; CHECK-NEXT: [[B:%.*]] = shl nuw nsw i64 [[A]], 8
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; CHECK-NEXT: ret i64 [[B]]
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;
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%A = and i64 %X, 312
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store i64 %A, i64* %P ; multiple uses of A.
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%B = shl i64 %A, 8
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ret i64 %B
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}
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define i32 @preserve1(i32 %x) {
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; CHECK-LABEL: @preserve1(
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; CHECK-NEXT: [[ADD3:%.*]] = add nsw i32 [[X:%.*]], 5
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; CHECK-NEXT: ret i32 [[ADD3]]
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;
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%add = add nsw i32 %x, 2
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%add3 = add nsw i32 %add, 3
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ret i32 %add3
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}
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define i8 @nopreserve1(i8 %x) {
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; CHECK-LABEL: @nopreserve1(
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; CHECK-NEXT: [[ADD3:%.*]] = add i8 [[X:%.*]], -126
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; CHECK-NEXT: ret i8 [[ADD3]]
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;
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%add = add nsw i8 %x, 127
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%add3 = add nsw i8 %add, 3
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ret i8 %add3
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}
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define i8 @nopreserve2(i8 %x) {
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; CHECK-LABEL: @nopreserve2(
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; CHECK-NEXT: [[ADD3:%.*]] = add i8 [[X:%.*]], 3
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; CHECK-NEXT: ret i8 [[ADD3]]
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;
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%add = add i8 %x, 1
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%add3 = add nsw i8 %add, 2
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ret i8 %add3
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}
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define i8 @nopreserve3(i8 %A, i8 %B) {
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; CHECK-LABEL: @nopreserve3(
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; CHECK-NEXT: [[Y:%.*]] = add i8 [[A:%.*]], [[B:%.*]]
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; CHECK-NEXT: [[ADD:%.*]] = add i8 [[Y]], 20
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; CHECK-NEXT: ret i8 [[ADD]]
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;
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%x = add i8 %A, 10
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%y = add i8 %B, 10
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%add = add nsw i8 %x, %y
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ret i8 %add
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}
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define i8 @nopreserve4(i8 %A, i8 %B) {
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; CHECK-LABEL: @nopreserve4(
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; CHECK-NEXT: [[Y:%.*]] = add i8 [[A:%.*]], [[B:%.*]]
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; CHECK-NEXT: [[ADD:%.*]] = add i8 [[Y]], 20
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; CHECK-NEXT: ret i8 [[ADD]]
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;
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%x = add nsw i8 %A, 10
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%y = add nsw i8 %B, 10
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%add = add nsw i8 %x, %y
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ret i8 %add
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}
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; TODO: computeKnownBits() should look through a shufflevector.
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define <3 x i32> @shl_nuw_nsw_shuffle_splat_vec(<2 x i8> %x) {
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; CHECK-LABEL: @shl_nuw_nsw_shuffle_splat_vec(
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; CHECK-NEXT: [[T2:%.*]] = zext <2 x i8> [[X:%.*]] to <2 x i32>
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; CHECK-NEXT: [[SHUF:%.*]] = shufflevector <2 x i32> [[T2]], <2 x i32> undef, <3 x i32> <i32 1, i32 0, i32 1>
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; CHECK-NEXT: [[T3:%.*]] = shl nsw <3 x i32> [[SHUF]], <i32 17, i32 17, i32 17>
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; CHECK-NEXT: ret <3 x i32> [[T3]]
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;
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%t2 = zext <2 x i8> %x to <2 x i32>
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%shuf = shufflevector <2 x i32> %t2, <2 x i32> undef, <3 x i32> <i32 1, i32 0, i32 1>
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%t3 = shl <3 x i32> %shuf, <i32 17, i32 17, i32 17>
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ret <3 x i32> %t3
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}
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; Negative test - if the shuffle mask contains an undef, we bail out to
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; avoid propagating information that may not be used consistently by callers.
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define <3 x i32> @shl_nuw_nsw_shuffle_undef_elt_splat_vec(<2 x i8> %x) {
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; CHECK-LABEL: @shl_nuw_nsw_shuffle_undef_elt_splat_vec(
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; CHECK-NEXT: [[T2:%.*]] = zext <2 x i8> [[X:%.*]] to <2 x i32>
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; CHECK-NEXT: [[SHUF:%.*]] = shufflevector <2 x i32> [[T2]], <2 x i32> undef, <3 x i32> <i32 1, i32 undef, i32 0>
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; CHECK-NEXT: [[T3:%.*]] = shl <3 x i32> [[SHUF]], <i32 17, i32 17, i32 17>
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; CHECK-NEXT: ret <3 x i32> [[T3]]
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;
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%t2 = zext <2 x i8> %x to <2 x i32>
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%shuf = shufflevector <2 x i32> %t2, <2 x i32> undef, <3 x i32> <i32 1, i32 undef, i32 0>
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%t3 = shl <3 x i32> %shuf, <i32 17, i32 17, i32 17>
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ret <3 x i32> %t3
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}
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