Index: llvm/trunk/lib/Transforms/Scalar/EarlyCSE.cpp =================================================================== --- llvm/trunk/lib/Transforms/Scalar/EarlyCSE.cpp +++ llvm/trunk/lib/Transforms/Scalar/EarlyCSE.cpp @@ -658,10 +658,25 @@ if (match(Inst, m_Intrinsic())) { if (auto *CondI = dyn_cast(cast(Inst)->getArgOperand(0))) { - // The condition we're on guarding here is true for all dominated - // locations. - if (SimpleValue::canHandle(CondI)) + if (SimpleValue::canHandle(CondI)) { + // Do we already know the actual value of this condition? + if (auto *KnownCond = AvailableValues.lookup(CondI)) { + // Is the condition known to be true? + if (isa(KnownCond) && + cast(KnownCond)->isOneValue()) { + DEBUG(dbgs() << "EarlyCSE removing guard: " << *Inst << '\n'); + removeMSSA(Inst); + Inst->eraseFromParent(); + Changed = true; + continue; + } else + // Use the known value if it wasn't true. + cast(Inst)->setArgOperand(0, KnownCond); + } + // The condition we're on guarding here is true for all dominated + // locations. AvailableValues.insert(CondI, ConstantInt::getTrue(BB->getContext())); + } } // Guard intrinsics read all memory, but don't write any memory. Index: llvm/trunk/test/Transforms/EarlyCSE/guards.ll =================================================================== --- llvm/trunk/test/Transforms/EarlyCSE/guards.ll +++ llvm/trunk/test/Transforms/EarlyCSE/guards.ll @@ -180,3 +180,159 @@ store i32 600, i32* %ptr ret void } + +define void @test07(i32 %a, i32 %b) { +; Check that we are able to remove the guards on the same condition even if the +; condition is not being recalculated. + +; CHECK-LABEL: @test07( +; CHECK-NEXT: %cmp = icmp eq i32 %a, %b +; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] +; CHECK-NEXT: ret void + + %cmp = icmp eq i32 %a, %b + call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] + call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] + call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] + ret void +} + +define void @test08(i32 %a, i32 %b, i32* %ptr) { +; Check that we deal correctly with stores when removing guards in the same +; block in case when the condition is not recalculated. + +; CHECK-LABEL: @test08( +; CHECK-NEXT: %cmp = icmp eq i32 %a, %b +; CHECK-NEXT: store i32 100, i32* %ptr +; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] +; CHECK-NEXT: store i32 400, i32* %ptr +; CHECK-NEXT: ret void + + %cmp = icmp eq i32 %a, %b + store i32 100, i32* %ptr + call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] + store i32 200, i32* %ptr + call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] + store i32 300, i32* %ptr + call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] + store i32 400, i32* %ptr + ret void +} + +define void @test09(i32 %a, i32 %b, i1 %c, i32* %ptr) { +; Similar to test08, but with more control flow. +; TODO: Can we get rid of the store in the end of entry given that it is +; post-dominated by other stores? + +; CHECK-LABEL: @test09( +; CHECK: entry: +; CHECK-NEXT: %cmp = icmp eq i32 %a, %b +; CHECK-NEXT: store i32 100, i32* %ptr +; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] +; CHECK-NEXT: store i32 400, i32* %ptr +; CHECK-NEXT: br i1 %c, label %if.true, label %if.false +; CHECK: if.true: +; CHECK-NEXT: store i32 500, i32* %ptr +; CHECK-NEXT: br label %merge +; CHECK: if.false: +; CHECK-NEXT: store i32 600, i32* %ptr +; CHECK-NEXT: br label %merge +; CHECK: merge: +; CHECK-NEXT: ret void + +entry: + %cmp = icmp eq i32 %a, %b + store i32 100, i32* %ptr + call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] + store i32 200, i32* %ptr + call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] + store i32 300, i32* %ptr + call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] + store i32 400, i32* %ptr + br i1 %c, label %if.true, label %if.false + +if.true: + call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] + store i32 500, i32* %ptr + br label %merge + +if.false: + call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] + store i32 600, i32* %ptr + br label %merge + +merge: + ret void +} + +define void @test10(i32 %a, i32 %b, i1 %c, i32* %ptr) { +; Make sure that non-dominating guards do not cause other guards removal. + +; CHECK-LABEL: @test10( +; CHECK: entry: +; CHECK-NEXT: %cmp = icmp eq i32 %a, %b +; CHECK-NEXT: br i1 %c, label %if.true, label %if.false +; CHECK: if.true: +; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] +; CHECK-NEXT: store i32 100, i32* %ptr +; CHECK-NEXT: br label %merge +; CHECK: if.false: +; CHECK-NEXT: store i32 200, i32* %ptr +; CHECK-NEXT: br label %merge +; CHECK: merge: +; CHECK-NEXT: store i32 300, i32* %ptr +; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] +; CHECK-NEXT: store i32 400, i32* %ptr +; CHECK-NEXT: ret void + +entry: + %cmp = icmp eq i32 %a, %b + br i1 %c, label %if.true, label %if.false + +if.true: + call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] + store i32 100, i32* %ptr + call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] + br label %merge + +if.false: + store i32 200, i32* %ptr + br label %merge + +merge: + store i32 300, i32* %ptr + call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] + store i32 400, i32* %ptr + ret void +} + +define void @test11(i32 %a, i32 %b, i32* %ptr) { +; Make sure that branching condition is applied to guards. + +; CHECK-LABEL: @test11( +; CHECK: entry: +; CHECK-NEXT: %cmp = icmp eq i32 %a, %b +; CHECK-NEXT: br i1 %cmp, label %if.true, label %if.false +; CHECK: if.true: +; CHECK-NEXT: br label %merge +; CHECK: if.false: +; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 false) [ "deopt"() ] +; CHECK-NEXT: br label %merge +; CHECK: merge: +; CHECK-NEXT: ret void + +entry: + %cmp = icmp eq i32 %a, %b + br i1 %cmp, label %if.true, label %if.false + +if.true: + call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] + br label %merge + +if.false: + call void (i1, ...) @llvm.experimental.guard(i1 %cmp) [ "deopt"() ] + br label %merge + +merge: + ret void +}