diff --git a/llvm/lib/Transforms/Scalar/LoopLoadElimination.cpp b/llvm/lib/Transforms/Scalar/LoopLoadElimination.cpp index f611ef6b2fa2d6..38aea1371e1e1a 100644 --- a/llvm/lib/Transforms/Scalar/LoopLoadElimination.cpp +++ b/llvm/lib/Transforms/Scalar/LoopLoadElimination.cpp @@ -448,6 +448,10 @@ class LoadEliminationForLoop { new LoadInst(Cand.Load->getType(), InitialPtr, "load_initial", /* isVolatile */ false, Cand.Load->getAlign(), PH->getTerminator()->getIterator()); + // We don't give any debug location to Initial, because it is inserted + // into the loop's preheader. A debug location inside the loop will cause + // a misleading stepping when debugging. The test update-debugloc-store + // -forwarded.ll checks this. PHINode *PHI = PHINode::Create(Initial->getType(), 2, "store_forwarded"); PHI->insertBefore(L->getHeader()->begin()); @@ -462,14 +466,20 @@ class LoadEliminationForLoop { "The type sizes should match!"); Value *StoreValue = Cand.Store->getValueOperand(); - if (LoadType != StoreType) + if (LoadType != StoreType) { StoreValue = CastInst::CreateBitOrPointerCast(StoreValue, LoadType, "store_forward_cast", Cand.Store->getIterator()); + // Because it casts the old `load` value and is used by the new `phi` + // which replaces the old `load`, we give the `load`'s debug location + // to it. + cast(StoreValue)->setDebugLoc(Cand.Load->getDebugLoc()); + } PHI->addIncoming(StoreValue, L->getLoopLatch()); Cand.Load->replaceAllUsesWith(PHI); + PHI->setDebugLoc(Cand.Load->getDebugLoc()); } /// Top-level driver for each loop: find store->load forwarding diff --git a/llvm/test/Transforms/LoopLoadElim/update-debugloc-store-forwarded.ll b/llvm/test/Transforms/LoopLoadElim/update-debugloc-store-forwarded.ll new file mode 100644 index 00000000000000..6833a3fd23cb46 --- /dev/null +++ b/llvm/test/Transforms/LoopLoadElim/update-debugloc-store-forwarded.ll @@ -0,0 +1,85 @@ +; RUN: opt -passes=loop-load-elim -S < %s | FileCheck %s + +; LoopLoadElimination's propagateStoredValueToLoadUsers() replaces the +; `load` (`%a`) with a hoisted initial `load` and a `phi` that forwards +; the stored value. +; This test checks that the debug location is propagated to the new `phi` +; from the original `load` it replaces in block `%for.body` and the debug +; location drop of the hoisted `load` in block `%entry`. +; Moreover, this test also checks the debug location update of the new +; `bitcast` created when the `load` type is mismatched with the `store` type: +; store i32 ... +; %a = load float, ... +; Because the `bitcast` casts the old `load` value, it has the same debug +; location as the old `load` (ie., the same as the new `phi`). + +; If the store and the load use different types, but have the same +; size then we should still be able to forward the value. +; +; for (unsigned i = 0; i < 100; i++) { +; A[i+1] = B[i] + 2; +; C[i] = ((float*)A)[i] * 2; +; } + +define void @f(ptr noalias %A, ptr noalias %B, ptr noalias %C, i64 %N) !dbg !5 { +; CHECK-LABEL: define void @f( +; CHECK-NEXT: entry: +; CHECK-NEXT: [[LOAD_INITIAL:%.*]] = load float, ptr {{.*}}, align 4{{$}} +; CHECK: for.body: +; CHECK-NEXT: [[STORE_FORWARDED:%.*]] = phi float [ [[LOAD_INITIAL]], %entry ], [ [[STORE_FORWARD_CAST:%.*]], %for.body ], !dbg [[DBG9:![0-9]+]] +; CHECK: [[STORE_FORWARD_CAST]] = bitcast i32 {{.*}} to float, !dbg [[DBG9]] +; CHECK: [[DBG9]] = !DILocation(line: 11, +; +entry: + br label %for.body, !dbg !8 + +for.body: ; preds = %for.body, %entry + %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ], !dbg !9 + %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1, !dbg !10 + %Aidx_next = getelementptr inbounds i32, ptr %A, i64 %indvars.iv.next, !dbg !11 + %Bidx = getelementptr inbounds i32, ptr %B, i64 %indvars.iv, !dbg !12 + %Cidx = getelementptr inbounds i32, ptr %C, i64 %indvars.iv, !dbg !13 + %Aidx = getelementptr inbounds i32, ptr %A, i64 %indvars.iv, !dbg !14 + %b = load i32, ptr %Bidx, align 4, !dbg !15 + %a_p1 = add i32 %b, 2, !dbg !16 + store i32 %a_p1, ptr %Aidx_next, align 4, !dbg !17 + %a = load float, ptr %Aidx, align 4, !dbg !18 + %c = fmul float %a, 2.000000e+00, !dbg !19 + %c.int = fptosi float %c to i32, !dbg !20 + store i32 %c.int, ptr %Cidx, align 4, !dbg !21 + %exitcond = icmp eq i64 %indvars.iv.next, %N, !dbg !22 + br i1 %exitcond, label %for.end, label %for.body, !dbg !23 + +for.end: ; preds = %for.body + ret void, !dbg !24 +} + +!llvm.dbg.cu = !{!0} +!llvm.debugify = !{!2, !3} +!llvm.module.flags = !{!4} + +!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug) +!1 = !DIFile(filename: "type-mismatch.ll", directory: "/") +!2 = !{i32 17} +!3 = !{i32 0} +!4 = !{i32 2, !"Debug Info Version", i32 3} +!5 = distinct !DISubprogram(name: "f", linkageName: "f", scope: null, file: !1, line: 1, type: !6, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0) +!6 = !DISubroutineType(types: !7) +!7 = !{} +!8 = !DILocation(line: 1, column: 1, scope: !5) +!9 = !DILocation(line: 2, column: 1, scope: !5) +!10 = !DILocation(line: 3, column: 1, scope: !5) +!11 = !DILocation(line: 4, column: 1, scope: !5) +!12 = !DILocation(line: 5, column: 1, scope: !5) +!13 = !DILocation(line: 6, column: 1, scope: !5) +!14 = !DILocation(line: 7, column: 1, scope: !5) +!15 = !DILocation(line: 8, column: 1, scope: !5) +!16 = !DILocation(line: 9, column: 1, scope: !5) +!17 = !DILocation(line: 10, column: 1, scope: !5) +!18 = !DILocation(line: 11, column: 1, scope: !5) +!19 = !DILocation(line: 12, column: 1, scope: !5) +!20 = !DILocation(line: 13, column: 1, scope: !5) +!21 = !DILocation(line: 14, column: 1, scope: !5) +!22 = !DILocation(line: 15, column: 1, scope: !5) +!23 = !DILocation(line: 16, column: 1, scope: !5) +!24 = !DILocation(line: 17, column: 1, scope: !5)