| ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py |
| ; RUN: opt < %s -passes=instsimplify -S | FileCheck %s |
| |
| ; %r = shl nuw i8 C, %x |
| ; As per langref: If the nuw keyword is present, then the shift produces |
| ; a poison value if it shifts out any non-zero bits. |
| ; Thus, if the sign bit is set on C, then %x can only be 0, which means that |
| ; %r can only be C. |
| |
| define i8 @shl_nuw (i8 %x) { |
| ; CHECK-LABEL: @shl_nuw( |
| ; CHECK-NEXT: ret i8 -1 |
| ; |
| %ret = shl nuw i8 -1, %x |
| ; nuw here means that %x can only be 0 |
| ret i8 %ret |
| } |
| |
| define i8 @shl_nuw_nsw (i8 %x) { |
| ; CHECK-LABEL: @shl_nuw_nsw( |
| ; CHECK-NEXT: ret i8 -1 |
| ; |
| %ret = shl nuw nsw i8 -1, %x |
| ; nuw here means that %x can only be 0 |
| ret i8 %ret |
| } |
| |
| define i8 @shl_128 (i8 %x) { |
| ; CHECK-LABEL: @shl_128( |
| ; CHECK-NEXT: ret i8 -128 |
| ; |
| %ret = shl nuw i8 128, %x |
| ; 128 == 1<<7 == just the sign bit is set |
| ret i8 %ret |
| } |
| |
| ; ============================================================================ ; |
| ; Positive tests with value range known |
| ; ============================================================================ ; |
| |
| declare void @llvm.assume(i1 %cond); |
| |
| define i8 @knownbits_negative(i8 %x, i8 %y) { |
| ; CHECK-LABEL: @knownbits_negative( |
| ; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[X:%.*]], 0 |
| ; CHECK-NEXT: tail call void @llvm.assume(i1 [[CMP]]) |
| ; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 [[X]], [[Y:%.*]] |
| ; CHECK-NEXT: ret i8 [[RET]] |
| ; |
| %cmp = icmp slt i8 %x, 0 |
| tail call void @llvm.assume(i1 %cmp) |
| %ret = shl nuw i8 %x, %y |
| ret i8 %ret |
| } |
| |
| define i8 @knownbits_negativeorzero(i8 %x, i8 %y) { |
| ; CHECK-LABEL: @knownbits_negativeorzero( |
| ; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[X:%.*]], 1 |
| ; CHECK-NEXT: tail call void @llvm.assume(i1 [[CMP]]) |
| ; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 [[X]], [[Y:%.*]] |
| ; CHECK-NEXT: ret i8 [[RET]] |
| ; |
| %cmp = icmp slt i8 %x, 1 |
| tail call void @llvm.assume(i1 %cmp) |
| %ret = shl nuw i8 %x, %y |
| ret i8 %ret |
| } |
| |
| ; ============================================================================ ; |
| ; Vectors |
| ; ============================================================================ ; |
| |
| define <2 x i8> @shl_vec(<2 x i8> %x) { |
| ; CHECK-LABEL: @shl_vec( |
| ; CHECK-NEXT: ret <2 x i8> <i8 -1, i8 -1> |
| ; |
| %ret = shl nuw <2 x i8> <i8 -1, i8 -1>, %x |
| ret <2 x i8> %ret |
| } |
| |
| define <3 x i8> @shl_vec_undef(<3 x i8> %x) { |
| ; CHECK-LABEL: @shl_vec_undef( |
| ; CHECK-NEXT: ret <3 x i8> <i8 -1, i8 undef, i8 -1> |
| ; |
| %ret = shl nuw <3 x i8> <i8 -1, i8 undef, i8 -1>, %x |
| ret <3 x i8> %ret |
| } |
| |
| define <2 x i8> @shl_vec_nonsplat(<2 x i8> %x) { |
| ; CHECK-LABEL: @shl_vec_nonsplat( |
| ; CHECK-NEXT: ret <2 x i8> <i8 -1, i8 -2> |
| ; |
| %ret = shl nuw <2 x i8> <i8 -1, i8 -2>, %x |
| ret <2 x i8> %ret |
| } |
| |
| ; ============================================================================ ; |
| ; Negative tests. Should not be folded. |
| ; ============================================================================ ; |
| |
| define i8 @shl_127 (i8 %x) { |
| ; CHECK-LABEL: @shl_127( |
| ; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 127, [[X:%.*]] |
| ; CHECK-NEXT: ret i8 [[RET]] |
| ; |
| %ret = shl nuw i8 127, %x |
| ; 127 == (1<<7)-1 == all bits except the sign bit are set. |
| ret i8 %ret |
| } |
| |
| define i8 @bad_shl (i8 %x) { |
| ; CHECK-LABEL: @bad_shl( |
| ; CHECK-NEXT: [[RET:%.*]] = shl i8 -1, [[X:%.*]] |
| ; CHECK-NEXT: ret i8 [[RET]] |
| ; |
| %ret = shl i8 -1, %x ; need nuw |
| ret i8 %ret |
| } |
| |
| define i8 @bad_nsw (i8 %x) { |
| ; CHECK-LABEL: @bad_nsw( |
| ; CHECK-NEXT: [[RET:%.*]] = shl nsw i8 -1, [[X:%.*]] |
| ; CHECK-NEXT: ret i8 [[RET]] |
| ; |
| %ret = shl nsw i8 -1, %x ; need nuw |
| ret i8 %ret |
| } |
| |
| ; First `shl` operand is not `-1` constant |
| |
| define i8 @bad_shl0(i8 %shlop1, i8 %x) { |
| ; CHECK-LABEL: @bad_shl0( |
| ; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 [[SHLOP1:%.*]], [[X:%.*]] |
| ; CHECK-NEXT: ret i8 [[RET]] |
| ; |
| %ret = shl nuw i8 %shlop1, %x |
| ret i8 %ret |
| } |
| |
| ; Bad shl nuw constant |
| |
| define i8 @bad_shl1(i8 %x) { |
| ; CHECK-LABEL: @bad_shl1( |
| ; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 1, [[X:%.*]] |
| ; CHECK-NEXT: ret i8 [[RET]] |
| ; |
| %ret = shl nuw i8 1, %x ; not -1 |
| ret i8 %ret |
| } |
| |
| define <2 x i8> @bad_shl_vec_nonsplat(<2 x i8> %x) { |
| ; CHECK-LABEL: @bad_shl_vec_nonsplat( |
| ; CHECK-NEXT: [[RET:%.*]] = shl nuw <2 x i8> <i8 -1, i8 1>, [[X:%.*]] |
| ; CHECK-NEXT: ret <2 x i8> [[RET]] |
| ; |
| %ret = shl nuw <2 x i8> <i8 -1, i8 1>, %x |
| ret <2 x i8> %ret |
| } |
| |
| ; Bad known bits |
| |
| define i8 @bad_knownbits(i8 %x, i8 %y) { |
| ; CHECK-LABEL: @bad_knownbits( |
| ; CHECK-NEXT: [[CMP:%.*]] = icmp slt i8 [[X:%.*]], 2 |
| ; CHECK-NEXT: tail call void @llvm.assume(i1 [[CMP]]) |
| ; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 [[X]], [[Y:%.*]] |
| ; CHECK-NEXT: ret i8 [[RET]] |
| ; |
| %cmp = icmp slt i8 %x, 2 |
| tail call void @llvm.assume(i1 %cmp) |
| %ret = shl nuw i8 %x, %y |
| ret i8 %ret |
| } |
| |
| define i8 @bad_knownbits_minusoneormore(i8 %x, i8 %y) { |
| ; CHECK-LABEL: @bad_knownbits_minusoneormore( |
| ; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i8 [[X:%.*]], -2 |
| ; CHECK-NEXT: tail call void @llvm.assume(i1 [[CMP]]) |
| ; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 [[X]], [[Y:%.*]] |
| ; CHECK-NEXT: ret i8 [[RET]] |
| ; |
| %cmp = icmp sgt i8 %x, -2 |
| tail call void @llvm.assume(i1 %cmp) |
| %ret = shl nuw i8 %x, %y |
| ret i8 %ret |
| } |
| |
| define i8 @bad_knownbits_zeroorpositive(i8 %x, i8 %y) { |
| ; CHECK-LABEL: @bad_knownbits_zeroorpositive( |
| ; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i8 [[X:%.*]], -1 |
| ; CHECK-NEXT: tail call void @llvm.assume(i1 [[CMP]]) |
| ; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 [[X]], [[Y:%.*]] |
| ; CHECK-NEXT: ret i8 [[RET]] |
| ; |
| %cmp = icmp sgt i8 %x, -1 |
| tail call void @llvm.assume(i1 %cmp) |
| %ret = shl nuw i8 %x, %y |
| ret i8 %ret |
| } |
| |
| define i8 @bad_knownbits_positive(i8 %x, i8 %y) { |
| ; CHECK-LABEL: @bad_knownbits_positive( |
| ; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i8 [[X:%.*]], 0 |
| ; CHECK-NEXT: tail call void @llvm.assume(i1 [[CMP]]) |
| ; CHECK-NEXT: [[RET:%.*]] = shl nuw i8 [[X]], [[Y:%.*]] |
| ; CHECK-NEXT: ret i8 [[RET]] |
| ; |
| %cmp = icmp sgt i8 %x, 0 |
| tail call void @llvm.assume(i1 %cmp) |
| %ret = shl nuw i8 %x, %y |
| ret i8 %ret |
| } |