From a87d3ba61c64bf957f2f9369e4d076cbbf3d486f Mon Sep 17 00:00:00 2001 From: Tim Northover Date: Thu, 10 Feb 2022 13:28:50 +0000 Subject: [PATCH] Reapply: StackProtector: ignore debug insts when splitting blocks. When deciding where to split a block to insert stack guard checks, we should move past any debug instructions we see that might (e.g.) be separating a tail call from its frame wrangling. This time, also don't run off the front of a basic block. --- llvm/lib/CodeGen/CodeGenCommonISel.cpp | 6 ++- .../AArch64/tailcall-ssp-split-debug.ll | 40 +++++++++++++++++++ .../CodeGen/X86/tailcall-ssp-split-debug.ll | 35 ++++++++++++++++ 3 files changed, 79 insertions(+), 2 deletions(-) create mode 100644 llvm/test/CodeGen/AArch64/tailcall-ssp-split-debug.ll create mode 100644 llvm/test/CodeGen/X86/tailcall-ssp-split-debug.ll diff --git a/llvm/lib/CodeGen/CodeGenCommonISel.cpp b/llvm/lib/CodeGen/CodeGenCommonISel.cpp index 877aa69c3e58..88b79d28175f 100644 --- a/llvm/lib/CodeGen/CodeGenCommonISel.cpp +++ b/llvm/lib/CodeGen/CodeGenCommonISel.cpp @@ -129,7 +129,9 @@ llvm::findSplitPointForStackProtector(MachineBasicBlock *BB, MachineBasicBlock::iterator Start = BB->begin(); MachineBasicBlock::iterator Previous = SplitPoint; - --Previous; + do { + --Previous; + } while (Previous != Start && Previous->isDebugInstr()); if (TII.isTailCall(*SplitPoint) && Previous->getOpcode() == TII.getCallFrameDestroyOpcode()) { @@ -142,7 +144,7 @@ llvm::findSplitPointForStackProtector(MachineBasicBlock *BB, // ADJCALLSTACKUP ... // TAILJMP somewhere // On the other hand, it could be an unrelated call in which case this tail - // call has to register moves of its own and should be the split point. For + // call has no register moves of its own and should be the split point. For // example: // ADJCALLSTACKDOWN // CALL something_else diff --git a/llvm/test/CodeGen/AArch64/tailcall-ssp-split-debug.ll b/llvm/test/CodeGen/AArch64/tailcall-ssp-split-debug.ll new file mode 100644 index 000000000000..b439fdbeb0da --- /dev/null +++ b/llvm/test/CodeGen/AArch64/tailcall-ssp-split-debug.ll @@ -0,0 +1,40 @@ +; RUN: llc -mtriple=arm64-apple-ios %s -o - | FileCheck %s + +define swifttailcc void @foo(i8* %call) ssp { +; CHECK-LABEL: foo: + %var = alloca [28 x i8], align 16 + br i1 undef, label %if.then, label %if.end + +if.then: + ret void + +if.end: + ; CHECK: mov x[[NULL:[0-9]+]], xzr + ; CHECK: ldr [[FPTR:x[0-9]+]], [x[[NULL]]] + ; CHECK: br [[FPTR]] + call void @llvm.dbg.value(metadata i8* %call, metadata !19, metadata !DIExpression()), !dbg !21 + %fptr = load void (i8*)*, void (i8*)** null, align 8 + musttail call swifttailcc void %fptr(i8* null) + ret void +} + +declare i8* @pthread_getspecific() + +; Function Attrs: nofree nosync nounwind readnone speculatable willreturn +declare void @llvm.dbg.value(metadata, metadata, metadata) #1 + +!llvm.module.flags = !{!2} +!llvm.dbg.cu = !{!11} + +!2 = !{i32 2, !"Debug Info Version", i32 3} +!11 = distinct !DICompileUnit(language: DW_LANG_C99, file: !12, producer: "Apple clang version 13.1.6 (clang-1316.0.17.4)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !13, splitDebugInlining: false, nameTableKind: None, sysroot: "/Library/Developer/CommandLineTools/SDKs/MacOSX12.3.sdk", sdk: "MacOSX12.3.sdk") +!12 = !DIFile(filename: "tmp.c", directory: "/Users/tim/llvm-internal/llvm-project/build") +!13 = !{} +!14 = !{!"Apple clang version 13.1.6 (clang-1316.0.17.4)"} +!15 = distinct !DISubprogram(name: "bar", scope: !12, file: !12, line: 3, type: !16, scopeLine: 3, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !11, retainedNodes: !18) +!16 = !DISubroutineType(types: !17) +!17 = !{null} +!18 = !{!19} +!19 = !DILocalVariable(name: "var", scope: !15, file: !12, line: 4, type: !20) +!20 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed) +!21 = !DILocation(line: 0, scope: !15) diff --git a/llvm/test/CodeGen/X86/tailcall-ssp-split-debug.ll b/llvm/test/CodeGen/X86/tailcall-ssp-split-debug.ll new file mode 100644 index 000000000000..19621a1e660f --- /dev/null +++ b/llvm/test/CodeGen/X86/tailcall-ssp-split-debug.ll @@ -0,0 +1,35 @@ +; RUN: llc -mtriple=x86_64-apple-macosx %s -o - | FileCheck %s + +define void @foo() ssp { +; CHECK-LABEL: foo: + %ptr = alloca [32 x i32], align 16 + br i1 undef, label %true, label %false + +true: + unreachable + +false: + call void @llvm.dbg.value(metadata i8** undef, metadata !19, metadata !DIExpression()) #2, !dbg !21 + ret void +} + +declare i8* @pthread_getspecific() + +; Function Attrs: nofree nosync nounwind readnone speculatable willreturn +declare void @llvm.dbg.value(metadata, metadata, metadata) #1 + +!llvm.module.flags = !{!2} +!llvm.dbg.cu = !{!11} + +!2 = !{i32 2, !"Debug Info Version", i32 3} +!11 = distinct !DICompileUnit(language: DW_LANG_C99, file: !12, producer: "Apple clang version 13.1.6 (clang-1316.0.17.4)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !13, splitDebugInlining: false, nameTableKind: None, sysroot: "/Library/Developer/CommandLineTools/SDKs/MacOSX12.3.sdk", sdk: "MacOSX12.3.sdk") +!12 = !DIFile(filename: "tmp.c", directory: "/Users/tim/llvm-internal/llvm-project/build") +!13 = !{} +!14 = !{!"Apple clang version 13.1.6 (clang-1316.0.17.4)"} +!15 = distinct !DISubprogram(name: "bar", scope: !12, file: !12, line: 3, type: !16, scopeLine: 3, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !11, retainedNodes: !18) +!16 = !DISubroutineType(types: !17) +!17 = !{null} +!18 = !{!19} +!19 = !DILocalVariable(name: "var", scope: !15, file: !12, line: 4, type: !20) +!20 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed) +!21 = !DILocation(line: 0, scope: !15)