Index: lib/Transforms/Scalar/LoopLoadElimination.cpp =================================================================== --- lib/Transforms/Scalar/LoopLoadElimination.cpp +++ lib/Transforms/Scalar/LoopLoadElimination.cpp @@ -534,6 +534,12 @@ } if (!Checks.empty() || !LAI.getPSE().getUnionPredicate().isAlwaysTrue()) { + if (LAI.hasConvergentOp()) { + LLVM_DEBUG(dbgs() << "Versioning is needed but not allowed with " + "convergent calls\n"); + return false; + } + auto *HeaderBB = L->getHeader(); auto *F = HeaderBB->getParent(); bool OptForSize = F->hasOptSize() || Index: test/Transforms/LoopLoadElim/convergent.ll =================================================================== --- /dev/null +++ test/Transforms/LoopLoadElim/convergent.ll @@ -0,0 +1,51 @@ +; RUN: opt -loop-load-elim -S < %s | FileCheck %s +; RUN: opt -passes=loop-load-elim -S < %s | FileCheck %s + +; Simple st->ld forwarding derived from a lexical forward dep, but +; can't introduce runtime checks with a convergent call. +; +; for (unsigned i = 0; i < 100; i++) { +; A[i+1] = convergent(B[i]) + 2; +; C[i] = A[i] * 2; +; } + +target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128" + +; CHECK-LABEL: @f_convergent( +; CHECK: call i32 @llvm.convergent( +; CHECK-NOT: call i32 @llvm.convergent( +define void @f_convergent(i32* %A, i32* %B, i32* %C, i64 %N) #0 { + +entry: + br label %for.body + +for.body: ; preds = %for.body, %entry + %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ] + %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1 + + %Aidx_next = getelementptr inbounds i32, i32* %A, i64 %indvars.iv.next + %Bidx = getelementptr inbounds i32, i32* %B, i64 %indvars.iv + %Cidx = getelementptr inbounds i32, i32* %C, i64 %indvars.iv + %Aidx = getelementptr inbounds i32, i32* %A, i64 %indvars.iv + + %b = load i32, i32* %Bidx, align 4 + %convergent.b = call i32 @llvm.convergent(i32 %b) + + %a_p1 = add i32 %convergent.b, 2 + store i32 %a_p1, i32* %Aidx_next, align 4 + + %a = load i32, i32* %Aidx, align 1 + %c = mul i32 %a, 2 + store i32 %c, i32* %Cidx, align 4 + + %exitcond = icmp eq i64 %indvars.iv.next, %N + br i1 %exitcond, label %for.end, label %for.body + +for.end: ; preds = %for.body + ret void +} + +declare i32 @llvm.convergent(i32) #1 + +attributes #0 = { nounwind convergent } +attributes #1 = { nounwind readnone convergent }