64 changes: 63 additions & 1 deletion llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/BranchProbabilityInfo.h"
#include "llvm/Analysis/CFG.h"
#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/FastISel.h"
#include "llvm/CodeGen/FunctionLoweringInfo.h"
#include "llvm/CodeGen/GCMetadata.h"
Expand All @@ -40,6 +41,7 @@
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
Expand Down Expand Up @@ -892,6 +894,8 @@ void SelectionDAGISel::DoInstructionSelection() {
void SelectionDAGISel::PrepareEHLandingPad() {
MachineBasicBlock *MBB = FuncInfo->MBB;

const TargetRegisterClass *PtrRC = TLI->getRegClassFor(TLI->getPointerTy());

// Add a label to mark the beginning of the landing pad. Deletion of the
// landing pad can thus be detected via the MachineModuleInfo.
MCSymbol *Label = MF->getMMI().addLandingPad(MBB);
Expand All @@ -903,8 +907,66 @@ void SelectionDAGISel::PrepareEHLandingPad() {
BuildMI(*MBB, FuncInfo->InsertPt, SDB->getCurDebugLoc(), II)
.addSym(Label);

if (TM.getMCAsmInfo()->getExceptionHandlingType() ==
ExceptionHandling::MSVC) {
// Make virtual registers and a series of labels that fill in values for the
// clauses.
auto &RI = MF->getRegInfo();
FuncInfo->ExceptionSelectorVirtReg = RI.createVirtualRegister(PtrRC);

// Get all invoke BBs that will unwind into the clause BBs.
SmallVector<MachineBasicBlock *, 4> InvokeBBs(MBB->pred_begin(),
MBB->pred_end());

// Emit separate machine basic blocks with separate labels for each clause
// before the main landing pad block.
const BasicBlock *LLVMBB = MBB->getBasicBlock();
const LandingPadInst *LPadInst = LLVMBB->getLandingPadInst();
MachineInstrBuilder SelectorPHI = BuildMI(
*MBB, MBB->begin(), SDB->getCurDebugLoc(), TII->get(TargetOpcode::PHI),
FuncInfo->ExceptionSelectorVirtReg);
for (unsigned I = 0, E = LPadInst->getNumClauses(); I != E; ++I) {
MachineBasicBlock *ClauseBB = MF->CreateMachineBasicBlock(LLVMBB);
MF->insert(MBB, ClauseBB);

// Add the edge from the invoke to the clause.
for (MachineBasicBlock *InvokeBB : InvokeBBs)
InvokeBB->addSuccessor(ClauseBB);

// Mark the clause as a landing pad or MI passes will delete it.
ClauseBB->setIsLandingPad();

GlobalValue *ClauseGV = ExtractTypeInfo(LPadInst->getClause(I));

// Start the BB with a label.
MCSymbol *ClauseLabel = MF->getMMI().addClauseForLandingPad(MBB);
BuildMI(*ClauseBB, ClauseBB->begin(), SDB->getCurDebugLoc(), II)
.addSym(ClauseLabel);

// Construct a simple BB that defines a register with the typeid constant.
FuncInfo->MBB = ClauseBB;
FuncInfo->InsertPt = ClauseBB->end();
unsigned VReg = SDB->visitLandingPadClauseBB(ClauseGV, MBB);
CurDAG->setRoot(SDB->getRoot());
SDB->clear();
CodeGenAndEmitDAG();

// Add the typeid virtual register to the phi in the main landing pad.
SelectorPHI.addReg(VReg).addMBB(ClauseBB);
}

// Remove the edge from the invoke to the lpad.
for (MachineBasicBlock *InvokeBB : InvokeBBs)
InvokeBB->removeSuccessor(MBB);

// Restore FuncInfo back to its previous state and select the main landing
// pad block.
FuncInfo->MBB = MBB;
FuncInfo->InsertPt = MBB->end();
return;
}

// Mark exception register as live in.
const TargetRegisterClass *PtrRC = TLI->getRegClassFor(TLI->getPointerTy());
if (unsigned Reg = TLI->getExceptionPointerRegister())
FuncInfo->ExceptionPointerVirtReg = MBB->addLiveIn(Reg, PtrRC);

Expand Down
175 changes: 175 additions & 0 deletions llvm/test/CodeGen/X86/seh-basic.ll
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; RUN: llc -mtriple x86_64-pc-windows-msvc < %s | FileCheck %s

define void @two_invoke_merged() {
entry:
invoke void @try_body()
to label %again unwind label %lpad

again:
invoke void @try_body()
to label %done unwind label %lpad

done:
ret void

lpad:
%vals = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @__C_specific_handler to i8*)
catch i8* bitcast (i32 (i8*, i8*)* @filt0 to i8*)
catch i8* bitcast (i32 (i8*, i8*)* @filt1 to i8*)
%sel = extractvalue { i8*, i32 } %vals, 1
call void @use_selector(i32 %sel)
ret void
}

; Normal path code

; CHECK-LABEL: {{^}}two_invoke_merged:
; CHECK: .seh_proc two_invoke_merged
; CHECK: .seh_handler __C_specific_handler, @unwind, @except
; CHECK: .Ltmp0:
; CHECK: callq try_body
; CHECK-NEXT: .Ltmp1:
; CHECK: .Ltmp2:
; CHECK: callq try_body
; CHECK-NEXT: .Ltmp3:
; CHECK: retq

; Landing pad code

; CHECK: .Ltmp5:
; CHECK: movl $1, %ecx
; CHECK: jmp
; CHECK: .Ltmp6:
; CHECK: movl $2, %ecx
; CHECK: callq use_selector

; CHECK: .seh_handlerdata
; CHECK-NEXT: .long 2
; CHECK-NEXT: .long .Ltmp0@IMGREL
; CHECK-NEXT: .long .Ltmp3@IMGREL+1
; CHECK-NEXT: .long filt0@IMGREL
; CHECK-NEXT: .long .Ltmp5@IMGREL
; CHECK-NEXT: .long .Ltmp0@IMGREL
; CHECK-NEXT: .long .Ltmp3@IMGREL+1
; CHECK-NEXT: .long filt1@IMGREL
; CHECK-NEXT: .long .Ltmp6@IMGREL
; CHECK: .text
; CHECK: .seh_endproc

define void @two_invoke_gap() {
entry:
invoke void @try_body()
to label %again unwind label %lpad

again:
call void @do_nothing_on_unwind()
invoke void @try_body()
to label %done unwind label %lpad

done:
ret void

lpad:
%vals = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @__C_specific_handler to i8*)
catch i8* bitcast (i32 (i8*, i8*)* @filt0 to i8*)
%sel = extractvalue { i8*, i32 } %vals, 1
call void @use_selector(i32 %sel)
ret void
}

; Normal path code

; CHECK-LABEL: {{^}}two_invoke_gap:
; CHECK: .seh_proc two_invoke_gap
; CHECK: .seh_handler __C_specific_handler, @unwind, @except
; CHECK: .Ltmp11:
; CHECK: callq try_body
; CHECK-NEXT: .Ltmp12:
; CHECK: callq do_nothing_on_unwind
; CHECK: .Ltmp13:
; CHECK: callq try_body
; CHECK-NEXT: .Ltmp14:
; CHECK: retq

; Landing pad code

; CHECK: .Ltmp16:
; CHECK: movl $1, %ecx
; CHECK: callq use_selector

; CHECK: .seh_handlerdata
; CHECK-NEXT: .long 2
; CHECK-NEXT: .long .Ltmp11@IMGREL
; CHECK-NEXT: .long .Ltmp12@IMGREL+1
; CHECK-NEXT: .long filt0@IMGREL
; CHECK-NEXT: .long .Ltmp16@IMGREL
; CHECK-NEXT: .long .Ltmp13@IMGREL
; CHECK-NEXT: .long .Ltmp14@IMGREL+1
; CHECK-NEXT: .long filt0@IMGREL
; CHECK-NEXT: .long .Ltmp16@IMGREL
; CHECK: .text
; CHECK: .seh_endproc

define void @two_invoke_nounwind_gap() {
entry:
invoke void @try_body()
to label %again unwind label %lpad

again:
call void @cannot_unwind()
invoke void @try_body()
to label %done unwind label %lpad

done:
ret void

lpad:
%vals = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @__C_specific_handler to i8*)
catch i8* bitcast (i32 (i8*, i8*)* @filt0 to i8*)
%sel = extractvalue { i8*, i32 } %vals, 1
call void @use_selector(i32 %sel)
ret void
}

; Normal path code

; CHECK-LABEL: {{^}}two_invoke_nounwind_gap:
; CHECK: .seh_proc two_invoke_nounwind_gap
; CHECK: .seh_handler __C_specific_handler, @unwind, @except
; CHECK: .Ltmp21:
; CHECK: callq try_body
; CHECK-NEXT: .Ltmp22:
; CHECK: callq cannot_unwind
; CHECK: .Ltmp23:
; CHECK: callq try_body
; CHECK-NEXT: .Ltmp24:
; CHECK: retq

; Landing pad code

; CHECK: .Ltmp26:
; CHECK: movl $1, %ecx
; CHECK: callq use_selector

; CHECK: .seh_handlerdata
; CHECK-NEXT: .long 1
; CHECK-NEXT: .long .Ltmp21@IMGREL
; CHECK-NEXT: .long .Ltmp24@IMGREL+1
; CHECK-NEXT: .long filt0@IMGREL
; CHECK-NEXT: .long .Ltmp26@IMGREL
; CHECK: .text
; CHECK: .seh_endproc

declare void @try_body()
declare void @do_nothing_on_unwind()
declare void @cannot_unwind() nounwind
declare void @use_selector(i32)

declare i32 @filt0(i8* %eh_info, i8* %rsp)
declare i32 @filt1(i8* %eh_info, i8* %rsp)

declare void @handler0()
declare void @handler1()

declare i32 @__C_specific_handler(...)
declare i32 @llvm.eh.typeid.for(i8*) readnone nounwind
196 changes: 196 additions & 0 deletions llvm/test/CodeGen/X86/seh-safe-div.ll
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; RUN: llc -mtriple x86_64-pc-windows-msvc < %s | FileCheck %s

; This test case is also intended to be run manually as a complete functional
; test. It should link, print something, and exit zero rather than crashing.
; It is the hypothetical lowering of a C source program that looks like:
;
; int safe_div(int *n, int *d) {
; int r;
; __try {
; __try {
; r = *n / *d;
; } __except(GetExceptionCode() == EXCEPTION_ACCESS_VIOLATION) {
; puts("EXCEPTION_ACCESS_VIOLATION");
; r = -1;
; }
; } __except(GetExceptionCode() == EXCEPTION_INT_DIVIDE_BY_ZERO) {
; puts("EXCEPTION_INT_DIVIDE_BY_ZERO");
; r = -2;
; }
; return r;
; }

@str1 = internal constant [27 x i8] c"EXCEPTION_ACCESS_VIOLATION\00"
@str2 = internal constant [29 x i8] c"EXCEPTION_INT_DIVIDE_BY_ZERO\00"

define i32 @safe_div(i32* %n, i32* %d) {
entry:
%r = alloca i32, align 4
invoke void @try_body(i32* %r, i32* %n, i32* %d)
to label %__try.cont unwind label %lpad

lpad:
%vals = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @__C_specific_handler to i8*)
catch i8* bitcast (i32 (i8*, i8*)* @safe_div_filt0 to i8*)
catch i8* bitcast (i32 (i8*, i8*)* @safe_div_filt1 to i8*)
%ehptr = extractvalue { i8*, i32 } %vals, 0
%sel = extractvalue { i8*, i32 } %vals, 1
%filt0_val = call i32 @llvm.eh.typeid.for(i8* bitcast (i32 (i8*, i8*)* @safe_div_filt0 to i8*))
%is_filt0 = icmp eq i32 %sel, %filt0_val
br i1 %is_filt0, label %handler0, label %eh.dispatch1

eh.dispatch1:
%filt1_val = call i32 @llvm.eh.typeid.for(i8* bitcast (i32 (i8*, i8*)* @safe_div_filt1 to i8*))
%is_filt1 = icmp eq i32 %sel, %filt1_val
br i1 %is_filt1, label %handler1, label %eh.resume

handler0:
call void @puts(i8* getelementptr ([27 x i8]* @str1, i32 0, i32 0))
store i32 -1, i32* %r, align 4
br label %__try.cont

handler1:
call void @puts(i8* getelementptr ([29 x i8]* @str2, i32 0, i32 0))
store i32 -2, i32* %r, align 4
br label %__try.cont

eh.resume:
resume { i8*, i32 } %vals

__try.cont:
%safe_ret = load i32* %r, align 4
ret i32 %safe_ret
}

; Normal path code

; CHECK: {{^}}safe_div:
; CHECK: .seh_proc safe_div
; CHECK: .seh_handler __C_specific_handler, @unwind, @except
; CHECK: .Ltmp0:
; CHECK: leaq [[rloc:.*\(%rsp\)]], %rcx
; CHECK: callq try_body
; CHECK-NEXT: .Ltmp1
; CHECK: .LBB0_7:
; CHECK: movl [[rloc]], %eax
; CHECK: retq

; Landing pad code

; CHECK: .Ltmp3:
; CHECK: movl $1, %[[sel:[a-z]+]]
; CHECK: .Ltmp4
; CHECK: movl $2, %[[sel]]
; CHECK: .L{{.*}}:
; CHECK: cmpl $1, %[[sel]]

; CHECK: # %handler0
; CHECK: callq puts
; CHECK: movl $-1, [[rloc]]
; CHECK: jmp .LBB0_7

; CHECK: cmpl $2, %[[sel]]

; CHECK: # %handler1
; CHECK: callq puts
; CHECK: movl $-2, [[rloc]]
; CHECK: jmp .LBB0_7

; FIXME: EH preparation should not call _Unwind_Resume.
; CHECK: callq _Unwind_Resume
; CHECK: ud2

; CHECK: .seh_handlerdata
; CHECK: .long 2
; CHECK: .long .Ltmp0@IMGREL
; CHECK: .long .Ltmp1@IMGREL+1
; CHECK: .long safe_div_filt0@IMGREL
; CHECK: .long .Ltmp3@IMGREL
; CHECK: .long .Ltmp0@IMGREL
; CHECK: .long .Ltmp1@IMGREL+1
; CHECK: .long safe_div_filt1@IMGREL
; CHECK: .long .Ltmp4@IMGREL
; CHECK: .text
; CHECK: .seh_endproc


define void @try_body(i32* %r, i32* %n, i32* %d) {
entry:
%0 = load i32* %n, align 4
%1 = load i32* %d, align 4
%div = sdiv i32 %0, %1
store i32 %div, i32* %r, align 4
ret void
}

; The prototype of these filter functions is:
; int filter(EXCEPTION_POINTERS *eh_ptrs, void *rbp);

; The definition of EXCEPTION_POINTERS is:
; typedef struct _EXCEPTION_POINTERS {
; EXCEPTION_RECORD *ExceptionRecord;
; CONTEXT *ContextRecord;
; } EXCEPTION_POINTERS;

; The definition of EXCEPTION_RECORD is:
; typedef struct _EXCEPTION_RECORD {
; DWORD ExceptionCode;
; ...
; } EXCEPTION_RECORD;

; The exception code can be retreived with two loads, one for the record
; pointer and one for the code. The values of local variables can be
; accessed via rbp, but that would require additional not yet implemented LLVM
; support.

define i32 @safe_div_filt0(i8* %eh_ptrs, i8* %rbp) {
%eh_ptrs_c = bitcast i8* %eh_ptrs to i32**
%eh_rec = load i32** %eh_ptrs_c
%eh_code = load i32* %eh_rec
; EXCEPTION_ACCESS_VIOLATION = 0xC0000005
%cmp = icmp eq i32 %eh_code, 3221225477
%filt.res = zext i1 %cmp to i32
ret i32 %filt.res
}

define i32 @safe_div_filt1(i8* %eh_ptrs, i8* %rbp) {
%eh_ptrs_c = bitcast i8* %eh_ptrs to i32**
%eh_rec = load i32** %eh_ptrs_c
%eh_code = load i32* %eh_rec
; EXCEPTION_INT_DIVIDE_BY_ZERO = 0xC0000094
%cmp = icmp eq i32 %eh_code, 3221225620
%filt.res = zext i1 %cmp to i32
ret i32 %filt.res
}

@str_result = internal constant [21 x i8] c"safe_div result: %d\0A\00"

define i32 @main() {
%d.addr = alloca i32, align 4
%n.addr = alloca i32, align 4

store i32 10, i32* %n.addr, align 4
store i32 2, i32* %d.addr, align 4
%r1 = call i32 @safe_div(i32* %n.addr, i32* %d.addr)
call void (i8*, ...)* @printf(i8* getelementptr ([21 x i8]* @str_result, i32 0, i32 0), i32 %r1)

store i32 10, i32* %n.addr, align 4
store i32 0, i32* %d.addr, align 4
%r2 = call i32 @safe_div(i32* %n.addr, i32* %d.addr)
call void (i8*, ...)* @printf(i8* getelementptr ([21 x i8]* @str_result, i32 0, i32 0), i32 %r2)

%r3 = call i32 @safe_div(i32* %n.addr, i32* null)
call void (i8*, ...)* @printf(i8* getelementptr ([21 x i8]* @str_result, i32 0, i32 0), i32 %r3)
ret i32 0
}

define void @_Unwind_Resume() {
call void @abort()
unreachable
}

declare i32 @__C_specific_handler(...)
declare i32 @llvm.eh.typeid.for(i8*) readnone nounwind
declare void @puts(i8*)
declare void @printf(i8*, ...)
declare void @abort()