Index: llvm/trunk/lib/Transforms/Utils/AddDiscriminators.cpp =================================================================== --- llvm/trunk/lib/Transforms/Utils/AddDiscriminators.cpp +++ llvm/trunk/lib/Transforms/Utils/AddDiscriminators.cpp @@ -102,6 +102,10 @@ return new AddDiscriminatorsLegacyPass(); } +static bool shouldHaveDiscriminator(const Instruction *I) { + return !isa(I) || isa(I); +} + /// \brief Assign DWARF discriminators. /// /// To assign discriminators, we examine the boundaries of every @@ -176,7 +180,13 @@ // discriminator for this instruction. for (BasicBlock &B : F) { for (auto &I : B.getInstList()) { - if (isa(&I)) + // Not all intrinsic calls should have a discriminator. + // We want to avoid a non-deterministic assignment of discriminators at + // different debug levels. We still allow discriminators on memory + // intrinsic calls because those can be early expanded by SROA into + // pairs of loads and stores, and the expanded load/store instructions + // should have a valid discriminator. + if (!shouldHaveDiscriminator(&I)) continue; const DILocation *DIL = I.getDebugLoc(); if (!DIL) @@ -207,6 +217,10 @@ LocationSet CallLocations; for (auto &I : B.getInstList()) { CallInst *Current = dyn_cast(&I); + // We bypass intrinsic calls for the following two reasons: + // 1) We want to avoid a non-deterministic assigment of + // discriminators. + // 2) We want to minimize the number of base discriminators used. if (!Current || isa(&I)) continue; Index: llvm/trunk/test/Transforms/AddDiscriminators/memcpy-discriminator.ll =================================================================== --- llvm/trunk/test/Transforms/AddDiscriminators/memcpy-discriminator.ll +++ llvm/trunk/test/Transforms/AddDiscriminators/memcpy-discriminator.ll @@ -0,0 +1,104 @@ +; RUN: opt < %s -add-discriminators -sroa -S | FileCheck %s + +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" + +; Test case obtained from the following C code: + +; struct A { +; int field1; +; short field2; +; }; +; +; struct B { +; struct A field1; +; int field2; +; }; +; +; +; extern struct B g_b; +; extern int bar(struct B b, int c); +; +; int foo(int cond) { +; int result = cond ? bar(g_b, 33) : 42; +; return result; +; } + +; In this test, global variable g_b is passed by copy to function bar. That +; copy is located on the stack (see alloca %g_b.coerce), and it is initialized +; by a memcpy call. +; +; SROA would split alloca %g_b.coerce into two (smaller disjoint) slices: +; slice [0,8) and slice [8, 12). Users of the original alloca are rewritten +; as users of the new alloca slices. +; In particular, the memcpy is rewritten by SROA as two load/store pairs. +; +; Later on, mem2reg successfully promotes the new alloca slices to registers, +; and loads %3 and %5 are made redundant by the loads obtained from the memcpy +; intrinsic expansion. +; +; If pass AddDiscriminators doesn't assign a discriminator to the intrinsic +; memcpy call, then the loads obtained from the memcpy expansion would not have +; a correct discriminator. +; +; This test checks that the two new loads inserted by SROA in %cond.true +; correctly reference a debug location with a non-zero discriminator. This test +; also checks that the same discriminator is used by all instructions from +; basic block %cond.true. + +%struct.B = type { %struct.A, i32 } +%struct.A = type { i32, i16 } + +@g_b = external global %struct.B, align 4 + +define i32 @foo(i32 %cond) #0 !dbg !5 { +entry: + %g_b.coerce = alloca { i64, i32 }, align 4 + %tobool = icmp ne i32 %cond, 0, !dbg !7 + br i1 %tobool, label %cond.true, label %cond.end, !dbg !7 + +cond.true: +; CHECK-LABEL: cond.true: +; CHECK: load i64, {{.*}}, !dbg ![[LOC:[0-9]+]] +; CHECK-NEXT: load i32, {{.*}}, !dbg ![[LOC]] +; CHECK-NEXT: %call = call i32 @bar({{.*}}), !dbg ![[LOC]] +; CHECK-NEXT: br label %cond.end, !dbg ![[BR_LOC:[0-9]+]] + +; CHECK-DAG: ![[LOC]] = !DILocation(line: 16, column: 23, scope: ![[SCOPE:[0-9]+]]) +; CHECK-DAG: ![[SCOPE]] = !DILexicalBlockFile({{.*}}, discriminator: 2) +; CHECK-DAG: ![[BR_LOC]] = !DILocation(line: 16, column: 16, scope: ![[SCOPE]]) + + %0 = bitcast { i64, i32 }* %g_b.coerce to i8*, !dbg !8 + %1 = bitcast %struct.B* @g_b to i8*, !dbg !8 + call void @llvm.memcpy.p0i8.p0i8.i64(i8* %0, i8* %1, i64 12, i32 4, i1 false), !dbg !8 + %2 = getelementptr inbounds { i64, i32 }, { i64, i32 }* %g_b.coerce, i32 0, i32 0, !dbg !8 + %3 = load i64, i64* %2, align 4, !dbg !8 + %4 = getelementptr inbounds { i64, i32 }, { i64, i32 }* %g_b.coerce, i32 0, i32 1, !dbg !8 + %5 = load i32, i32* %4, align 4, !dbg !8 + %call = call i32 @bar(i64 %3, i32 %5, i32 33), !dbg !8 + br label %cond.end, !dbg !7 + +cond.end: ; preds = %entry, %cond.true + %cond1 = phi i32 [ %call, %cond.true ], [ 42, %entry ], !dbg !7 + ret i32 %cond1, !dbg !9 +} + +declare i32 @bar(i64, i32, i32) + +declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture writeonly, i8* nocapture readonly, i64, i32, i1) #1 + +attributes #0 = { noinline nounwind uwtable } +attributes #1 = { argmemonly nounwind } + +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!3, !4} + +!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, isOptimized: false, runtimeVersion: 0, emissionKind: LineTablesOnly, enums: !2) +!1 = !DIFile(filename: "test.c", directory: ".") +!2 = !{} +!3 = !{i32 2, !"Dwarf Version", i32 4} +!4 = !{i32 2, !"Debug Info Version", i32 3} +!5 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 15, type: !6, isLocal: false, isDefinition: true, scopeLine: 15, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2) +!6 = !DISubroutineType(types: !2) +!7 = !DILocation(line: 16, column: 16, scope: !5) +!8 = !DILocation(line: 16, column: 23, scope: !5) +!9 = !DILocation(line: 17, column: 3, scope: !5)