diff options
Diffstat (limited to 'llvm')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp | 10 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/minmax-demandbits.ll | 12 |
2 files changed, 13 insertions, 9 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp index 18a2b2fdbfe..45cacc73d63 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp @@ -325,6 +325,16 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask, unsigned CTZ = DemandedMask.countTrailingZeros(); if (match(RHS, m_APInt(C)) && CTZ >= C->getActiveBits()) return LHS; + } else if (SPF == SPF_UMIN) { + // UMin(A, C) == A if ... + // The lowest non-zero bit of DemandMask is higher than the highest + // non-one bit of C. + // This comes from using DeMorgans on the above umax example. + const APInt *C; + unsigned CTZ = DemandedMask.countTrailingZeros(); + if (match(RHS, m_APInt(C)) && + CTZ >= C->getBitWidth() - C->countLeadingOnes()) + return LHS; } // If this is a select as part of any other min/max pattern, don't simplify diff --git a/llvm/test/Transforms/InstCombine/minmax-demandbits.ll b/llvm/test/Transforms/InstCombine/minmax-demandbits.ll index f838560f965..29a569663d2 100644 --- a/llvm/test/Transforms/InstCombine/minmax-demandbits.ll +++ b/llvm/test/Transforms/InstCombine/minmax-demandbits.ll @@ -190,9 +190,7 @@ define i32 @or_umin(i32 %A) { define i8 @or_min_31_30(i8 %A) { ; CHECK-LABEL: @or_min_31_30( -; CHECK-NEXT: [[CMP:%.*]] = icmp ult i8 [[A:%.*]], -30 -; CHECK-NEXT: [[MIN:%.*]] = select i1 [[CMP]], i8 [[A]], i8 -30 -; CHECK-NEXT: [[R:%.*]] = or i8 [[MIN]], 31 +; CHECK-NEXT: [[R:%.*]] = or i8 [[A:%.*]], 31 ; CHECK-NEXT: ret i8 [[R]] ; %cmp = icmp ult i8 %A, -30 @@ -203,9 +201,7 @@ define i8 @or_min_31_30(i8 %A) { define i8 @and_min_7_7(i8 %A) { ; CHECK-LABEL: @and_min_7_7( -; CHECK-NEXT: [[L2:%.*]] = icmp ult i8 [[A:%.*]], -7 -; CHECK-NEXT: [[MIN:%.*]] = select i1 [[L2]], i8 [[A]], i8 -7 -; CHECK-NEXT: [[R:%.*]] = and i8 [[MIN]], -8 +; CHECK-NEXT: [[R:%.*]] = and i8 [[A:%.*]], -8 ; CHECK-NEXT: ret i8 [[R]] ; %l2 = icmp ult i8 %A, -7 @@ -216,9 +212,7 @@ define i8 @and_min_7_7(i8 %A) { define i8 @and_min_7_8(i8 %A) { ; CHECK-LABEL: @and_min_7_8( -; CHECK-NEXT: [[L2:%.*]] = icmp ult i8 [[A:%.*]], -8 -; CHECK-NEXT: [[MIN:%.*]] = select i1 [[L2]], i8 [[A]], i8 -8 -; CHECK-NEXT: [[R:%.*]] = and i8 [[MIN]], -8 +; CHECK-NEXT: [[R:%.*]] = and i8 [[A:%.*]], -8 ; CHECK-NEXT: ret i8 [[R]] ; %l2 = icmp ult i8 %A, -8 |
