[llvm] r206684 - Patch by Vadim Chugunov
Yaron Keren
yaron.keren at gmail.com
Sat Apr 19 06:47:45 PDT 2014
Author: yrnkrn
Date: Sat Apr 19 08:47:43 2014
New Revision: 206684
URL: http://llvm.org/viewvc/llvm-project?rev=206684&view=rev
Log:
Patch by Vadim Chugunov
Win64 stack unwinder gets confused when execution flow "falls through" after
a call to 'noreturn' function. This fixes the "missing epilogue" problem by
emitting a trap instruction for IR 'unreachable' on x86_x64-pc-windows.
A secondary use for it would be for anyone wanting to make double-sure that
'noreturn' functions, indeed, do not return.
Modified:
llvm/trunk/include/llvm/Target/TargetOptions.h
llvm/trunk/lib/CodeGen/SelectionDAG/FastISel.cpp
llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
llvm/trunk/lib/Target/X86/X86TargetMachine.cpp
llvm/trunk/test/CodeGen/X86/br-fold.ll
Modified: llvm/trunk/include/llvm/Target/TargetOptions.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Target/TargetOptions.h?rev=206684&r1=206683&r2=206684&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Target/TargetOptions.h (original)
+++ llvm/trunk/include/llvm/Target/TargetOptions.h Sat Apr 19 08:47:43 2014
@@ -51,6 +51,7 @@ namespace llvm {
EnableFastISel(false), PositionIndependentExecutable(false),
UseInitArray(false),
DisableIntegratedAS(false), CompressDebugSections(false),
+ TrapUnreachable(false),
TrapFuncName(""), FloatABIType(FloatABI::Default),
AllowFPOpFusion(FPOpFusion::Standard) {}
@@ -162,6 +163,9 @@ namespace llvm {
/// Compress DWARF debug sections.
unsigned CompressDebugSections : 1;
+ /// Emit target-specific trap instruction for 'unreachable' IR instructions.
+ unsigned TrapUnreachable : 1;
+
/// getTrapFunctionName - If this returns a non-empty string, this means
/// isel should lower Intrinsic::trap to a call to the specified function
/// name instead of an ISD::TRAP node.
@@ -216,6 +220,7 @@ inline bool operator==(const TargetOptio
ARE_EQUAL(EnableFastISel) &&
ARE_EQUAL(PositionIndependentExecutable) &&
ARE_EQUAL(UseInitArray) &&
+ ARE_EQUAL(TrapUnreachable) &&
ARE_EQUAL(TrapFuncName) &&
ARE_EQUAL(FloatABIType) &&
ARE_EQUAL(AllowFPOpFusion);
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/FastISel.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/FastISel.cpp?rev=206684&r1=206683&r2=206684&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/FastISel.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/FastISel.cpp Sat Apr 19 08:47:43 2014
@@ -1041,8 +1041,10 @@ FastISel::SelectOperator(const User *I,
}
case Instruction::Unreachable:
- // Nothing to emit.
- return true;
+ if (TM.Options.TrapUnreachable)
+ return FastEmit_(MVT::Other, MVT::Other, ISD::TRAP) != 0;
+ else
+ return true;
case Instruction::Alloca:
// FunctionLowering has the static-sized case covered.
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp?rev=206684&r1=206683&r2=206684&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp Sat Apr 19 08:47:43 2014
@@ -2765,6 +2765,11 @@ void SelectionDAGBuilder::visitIndirectB
getValue(I.getAddress())));
}
+void SelectionDAGBuilder::visitUnreachable(const UnreachableInst &I) {
+ if (DAG.getTarget().Options.TrapUnreachable)
+ DAG.setRoot(DAG.getNode(ISD::TRAP, getCurSDLoc(), MVT::Other, DAG.getRoot()));
+}
+
void SelectionDAGBuilder::visitFSub(const User &I) {
// -0.0 - X --> fneg
Type *Ty = I.getType();
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h?rev=206684&r1=206683&r2=206684&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h Sat Apr 19 08:47:43 2014
@@ -642,7 +642,7 @@ private:
void visitBr(const BranchInst &I);
void visitSwitch(const SwitchInst &I);
void visitIndirectBr(const IndirectBrInst &I);
- void visitUnreachable(const UnreachableInst &I) { /* noop */ }
+ void visitUnreachable(const UnreachableInst &I);
// Helpers for visitSwitch
bool handleSmallSwitchRange(CaseRec& CR,
Modified: llvm/trunk/lib/Target/X86/X86TargetMachine.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86TargetMachine.cpp?rev=206684&r1=206683&r2=206684&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86TargetMachine.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86TargetMachine.cpp Sat Apr 19 08:47:43 2014
@@ -108,6 +108,13 @@ X86TargetMachine::X86TargetMachine(const
if (Options.FloatABIType == FloatABI::Default)
this->Options.FloatABIType = FloatABI::Hard;
+ // Windows stack unwinder gets confused when execution flow "falls through"
+ // after a call to 'noreturn' function.
+ // To prevent that, we emit a trap for 'unreachable' IR instructions.
+ // (which on X86, happens to be the 'ud2' instruction)
+ if (Subtarget.isTargetWin64())
+ this->Options.TrapUnreachable = true;
+
initAsmInfo();
}
Modified: llvm/trunk/test/CodeGen/X86/br-fold.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/br-fold.ll?rev=206684&r1=206683&r2=206684&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/br-fold.ll (original)
+++ llvm/trunk/test/CodeGen/X86/br-fold.ll Sat Apr 19 08:47:43 2014
@@ -1,7 +1,19 @@
-; RUN: llc -march=x86-64 < %s | FileCheck %s
+; RUN: llc -mtriple=x86_64-apple-darwin < %s | FileCheck -check-prefix=X64_DARWIN %s
+; RUN: llc -mtriple=x86_64-pc-linux < %s | FileCheck -check-prefix=X64_LINUX %s
+; RUN: llc -mtriple=x86_64-pc-windows < %s | FileCheck -check-prefix=X64_WINDOWS %s
+; RUN: llc -mtriple=x86_64-pc-windows-gnu < %s | FileCheck -check-prefix=X64_WINDOWS_GNU %s
-; CHECK: orq
-; CHECK-NEXT: %bb8.i329
+; X64_DARWIN: orq
+; X64_DARWIN-NEXT: %bb8.i329
+
+; X64_LINUX: orq %rax, %rcx
+; X64_LINUX-NEXT: %bb8.i329
+
+; X64_WINDOWS: orq %rax, %rcx
+; X64_WINDOWS-NEXT: ud2
+
+; X64_WINDOWS_GNU: orq %rax, %rcx
+; X64_WINDOWS_GNU-NEXT: ud2
@_ZN11xercesc_2_513SchemaSymbols21fgURI_SCHEMAFORSCHEMAE = external constant [33 x i16], align 32 ; <[33 x i16]*> [#uses=1]
@_ZN11xercesc_2_56XMLUni16fgNotationStringE = external constant [9 x i16], align 16 ; <[9 x i16]*> [#uses=1]
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