Index: lib/Transforms/Utils/SimplifyIndVar.cpp =================================================================== --- lib/Transforms/Utils/SimplifyIndVar.cpp +++ lib/Transforms/Utils/SimplifyIndVar.cpp @@ -156,6 +156,7 @@ void SimplifyIndvar::eliminateIVComparison(ICmpInst *ICmp, Value *IVOperand) { unsigned IVOperIdx = 0; ICmpInst::Predicate Pred = ICmp->getPredicate(); + ICmpInst::Predicate OriginalPred = Pred; if (IVOperand != ICmp->getOperand(0)) { // Swapped assert(IVOperand == ICmp->getOperand(1) && "Can't find IVOperand"); @@ -264,6 +265,16 @@ ICmp->setPredicate(InvariantPredicate); ICmp->setOperand(0, NewLHS); ICmp->setOperand(1, NewRHS); + } else if (ICmpInst::isSigned(OriginalPred) && + SE->isKnownNonNegative(S) && SE->isKnownNonNegative(X)) { + // If we were unable to make anything above, all we can is to canonicalize + // the comparison hoping that it will open the doors for other + // optimizations. If we find out that we compare two non-negative values, + // we turn the instruction's predicate to its unsigned version. Note that + // we cannot rely on Pred here unless we check if we have swapped it. + assert(ICmp->getPredicate() == OriginalPred && "Predicate changed?"); + DEBUG(dbgs() << "INDVARS: Turn to unsigned comparison: " << *ICmp << '\n'); + ICmp->setPredicate(ICmpInst::getUnsignedPredicate(OriginalPred)); } else return; Index: test/Analysis/ScalarEvolution/guards.ll =================================================================== --- test/Analysis/ScalarEvolution/guards.ll +++ test/Analysis/ScalarEvolution/guards.ll @@ -19,7 +19,7 @@ loop: ; CHECK: loop: ; CHECK: call void (i1, ...) @llvm.experimental.guard(i1 true) [ "deopt"() ] -; CHECK: %iv.inc.cmp = icmp slt i32 %iv.inc, %len +; CHECK: %iv.inc.cmp = icmp ult i32 %iv.inc, %len ; CHECK: call void (i1, ...) @llvm.experimental.guard(i1 %iv.inc.cmp) [ "deopt"() ] ; CHECK: leave: @@ -41,7 +41,7 @@ define void @test_2(i32 %n, i32* %len_buf) { ; CHECK-LABEL: @test_2( -; CHECK: [[LEN_SEXT:%[^ ]+]] = sext i32 %len to i64 +; CHECK: [[LEN_ZEXT:%[^ ]+]] = zext i32 %len to i64 ; CHECK: br label %loop entry: @@ -52,7 +52,7 @@ ; CHECK: loop: ; CHECK: %indvars.iv = phi i64 [ %indvars.iv.next, %loop ], [ 0, %entry ] ; CHECK: %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1 -; CHECK: %iv.inc.cmp = icmp slt i64 %indvars.iv.next, [[LEN_SEXT]] +; CHECK: %iv.inc.cmp = icmp ult i64 %indvars.iv.next, [[LEN_ZEXT]] ; CHECK: call void (i1, ...) @llvm.experimental.guard(i1 %iv.inc.cmp) [ "deopt"() ] ; CHECK: leave: Index: test/Transforms/IndVarSimplify/canonicalize-cmp.ll =================================================================== --- test/Transforms/IndVarSimplify/canonicalize-cmp.ll +++ test/Transforms/IndVarSimplify/canonicalize-cmp.ll @@ -0,0 +1,98 @@ +; RUN: opt -S -indvars < %s | FileCheck %s + +; Check that we replace signed comparisons between non-negative values with +; unsigned comparisons if we can. + +target datalayout = "n8:16:32:64" + +define i32 @test_01(i32 %a, i32 %b, i32* %p) { + +; CHECK-LABEL: @test_01( +; CHECK-NOT: icmp slt +; CHECK: %cmp1 = icmp ult i32 %iv, 100 +; CHECK: %cmp2 = icmp ult i32 %iv, 100 +; CHECK-NOT: %cmp3 +; CHECK: %exitcond = icmp ne i32 %iv.next, 1000 + +entry: + br label %loop.entry + +loop.entry: + %iv = phi i32 [ 0, %entry ], [ %iv.next, %loop.be ] + %cmp1 = icmp slt i32 %iv, 100 + br i1 %cmp1, label %b1, label %b2 + +b1: + store i32 %iv, i32* %p + br label %merge + +b2: + store i32 %a, i32* %p + br label %merge + +merge: + %cmp2 = icmp ult i32 %iv, 100 + br i1 %cmp2, label %b3, label %b4 + +b3: + store i32 %iv, i32* %p + br label %loop.be + +b4: + store i32 %b, i32* %p + br label %loop.be + +loop.be: + %iv.next = add i32 %iv, 1 + %cmp3 = icmp slt i32 %iv.next, 1000 + br i1 %cmp3, label %loop.entry, label %exit + +exit: + ret i32 %iv +} + +define i32 @test_02(i32 %a, i32 %b, i32* %p) { + +; CHECK-LABEL: @test_02( +; CHECK-NOT: icmp sgt +; CHECK: %cmp1 = icmp ugt i32 100, %iv +; CHECK: %cmp2 = icmp ugt i32 100, %iv +; CHECK-NOT: %cmp3 +; CHECK: %exitcond = icmp ne i32 %iv.next, 1000 + +entry: + br label %loop.entry + +loop.entry: + %iv = phi i32 [ 0, %entry ], [ %iv.next, %loop.be ] + %cmp1 = icmp sgt i32 100, %iv + br i1 %cmp1, label %b1, label %b2 + +b1: + store i32 %iv, i32* %p + br label %merge + +b2: + store i32 %a, i32* %p + br label %merge + +merge: + %cmp2 = icmp ugt i32 100, %iv + br i1 %cmp2, label %b3, label %b4 + +b3: + store i32 %iv, i32* %p + br label %loop.be + +b4: + store i32 %b, i32* %p + br label %loop.be + +loop.be: + %iv.next = add i32 %iv, 1 + %cmp3 = icmp sgt i32 1000, %iv.next + br i1 %cmp3, label %loop.entry, label %exit + +exit: + ret i32 %iv +} Index: test/Transforms/IndVarSimplify/eliminate-comparison.ll =================================================================== --- test/Transforms/IndVarSimplify/eliminate-comparison.ll +++ test/Transforms/IndVarSimplify/eliminate-comparison.ll @@ -111,7 +111,7 @@ ; Indvars should not turn the second loop into an infinite one. ; CHECK-LABEL: @func_11( -; CHECK: %tmp5 = icmp slt i32 %__key6.0, 10 +; CHECK: %tmp5 = icmp ult i32 %__key6.0, 10 ; CHECK-NOT: br i1 true, label %noassert68, label %unrolledend define i32 @func_11() nounwind uwtable { @@ -163,7 +163,7 @@ ; In this case the second loop only has a single iteration, fold the header away ; CHECK-LABEL: @func_12( -; CHECK: %tmp5 = icmp slt i32 %__key6.0, 10 +; CHECK: %tmp5 = icmp ult i32 %__key6.0, 10 ; CHECK: br i1 true, label %noassert68, label %unrolledend define i32 @func_12() nounwind uwtable { entry: Index: test/Transforms/IndVarSimplify/widen-loop-comp.ll =================================================================== --- test/Transforms/IndVarSimplify/widen-loop-comp.ll +++ test/Transforms/IndVarSimplify/widen-loop-comp.ll @@ -64,7 +64,7 @@ ; CHECK-LABEL: @test2 ; CHECK: for.body4.us ; CHECK: %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1 -; CHECK: %cmp2.us = icmp slt i64 +; CHECK: %cmp2.us = icmp ult i64 ; CHECK-NOT: %2 = trunc i64 %indvars.iv.next to i32 ; CHECK-NOT: %cmp2.us = icmp slt i32