Index: lib/Transforms/InstCombine/InstCombineSelect.cpp =================================================================== --- lib/Transforms/InstCombine/InstCombineSelect.cpp +++ lib/Transforms/InstCombine/InstCombineSelect.cpp @@ -651,11 +651,27 @@ return ReplaceInstUsesWith(Outer, C); } - // TODO: MIN(MIN(A, 23), 97) + // MIN(MIN(A, 23), 97) -> MIN(A, 23) + // MAX(MAX(A, 97), 23) -> MAX(A, 97) + if (SPF1 == SPF2) { + if (ConstantInt *CB = dyn_cast(B)) { + if (ConstantInt *CC = dyn_cast(C)) { + APInt ACB = CB->getValue(); + APInt ACC = CC->getValue(); + if ((SPF1 == SPF_UMIN && ACB.ule(ACC)) || + (SPF1 == SPF_SMIN && ACB.sle(ACC)) || + (SPF1 == SPF_UMAX && ACB.uge(ACC)) || + (SPF1 == SPF_SMAX && ACB.sge(ACC))) + return ReplaceInstUsesWith(Outer, Inner); + } + } + } + + // TODO: MIN(MIN(A, 97), 23) -> MIN(A, 23) + // TODO: MAX(MAX(A, 23), 97) -> MAX(A, 97) return nullptr; } - /// foldSelectICmpAnd - If one of the constants is zero (we know they can't /// both be) and we have an icmp instruction with zero, and we have an 'and' /// with the non-constant value and a power of two we can turn the select Index: test/Transforms/InstCombine/select.ll =================================================================== --- test/Transforms/InstCombine/select.ll +++ test/Transforms/InstCombine/select.ll @@ -1031,3 +1031,51 @@ ; CHECK: lshr exact i32 %2, 1 ; CHECK: xor i32 %3, 42 } + +; SMIN(SMIN(X, 11), 92) -> SMIN(X, 11) +define i32 @test68(i32 %x) { +entry: + %cmp = icmp slt i32 11, %x + %cond = select i1 %cmp, i32 11, i32 %x + %cmp3 = icmp slt i32 92, %cond + %retval = select i1 %cmp3, i32 92, i32 %cond + ret i32 %retval +; CHECK-LABEL: @test68( +; CHECK: ret i32 %cond +} + +; MIN(MIN(X, 24), 83) -> MIN(X, 24) +define i32 @test69(i32 %x) { +entry: + %cmp = icmp ult i32 24, %x + %cond = select i1 %cmp, i32 24, i32 %x + %cmp3 = icmp ult i32 83, %cond + %retval = select i1 %cmp3, i32 83, i32 %cond + ret i32 %retval +; CHECK-LABEL: @test69( +; CHECK: ret i32 %cond +} + +; SMAX(SMAX(X, 75), 36) -> SMAX(X, 75) +define i32 @test70(i32 %x) { +entry: + %cmp = icmp slt i32 %x, 75 + %cond = select i1 %cmp, i32 75, i32 %x + %cmp3 = icmp slt i32 %cond, 36 + %retval = select i1 %cmp3, i32 36, i32 %cond + ret i32 %retval +; CHECK-LABEL: @test70( +; CHECK: ret i32 %cond +} + +; MAX(MAX(X, 68), 47) -> MAX(X, 68) +define i32 @test71(i32 %x) { +entry: + %cmp = icmp ult i32 %x, 68 + %cond = select i1 %cmp, i32 68, i32 %x + %cmp3 = icmp ult i32 %cond, 47 + %retval = select i1 %cmp3, i32 47, i32 %cond + ret i32 %retval +; CHECK-LABEL: @test71( +; CHECK: ret i32 %cond +} \ No newline at end of file