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https://github.com/c64scene-ar/llvm-6502.git
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504fa89c8e
This adds handling for ExceptionHandling::MSVC, used by the x86_64-pc-windows-msvc triple. It assumes that filter functions have already been outlined in either the frontend or the backend. Filter functions are used in place of the landingpad catch clause type info operands. In catch clause order, the first filter to return true will catch the exception. The C specific handler table expects the landing pad to be split into one block per handler, but LLVM IR uses a single landing pad for all possible unwind actions. This patch papers over the mismatch by synthesizing single instruction BBs for every catch clause to fill in the EH selector that the landing pad block expects. Missing functionality: - Accessing data in the parent frame from outlined filters - Cleanups (from __finally) are unsupported, as they will require outlining and parent frame access - Filter clauses are unsupported, as there's no clear analogue in SEH In other words, this is the minimal set of changes needed to write IR to catch arbitrary exceptions and resume normal execution. Reviewers: majnemer Differential Revision: http://reviews.llvm.org/D6300 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225904 91177308-0d34-0410-b5e6-96231b3b80d8
197 lines
5.6 KiB
LLVM
197 lines
5.6 KiB
LLVM
; RUN: llc -mtriple x86_64-pc-windows-msvc < %s | FileCheck %s
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; This test case is also intended to be run manually as a complete functional
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; test. It should link, print something, and exit zero rather than crashing.
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; It is the hypothetical lowering of a C source program that looks like:
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;
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; int safe_div(int *n, int *d) {
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; int r;
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; __try {
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; __try {
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; r = *n / *d;
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; } __except(GetExceptionCode() == EXCEPTION_ACCESS_VIOLATION) {
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; puts("EXCEPTION_ACCESS_VIOLATION");
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; r = -1;
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; }
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; } __except(GetExceptionCode() == EXCEPTION_INT_DIVIDE_BY_ZERO) {
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; puts("EXCEPTION_INT_DIVIDE_BY_ZERO");
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; r = -2;
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; }
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; return r;
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; }
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@str1 = internal constant [27 x i8] c"EXCEPTION_ACCESS_VIOLATION\00"
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@str2 = internal constant [29 x i8] c"EXCEPTION_INT_DIVIDE_BY_ZERO\00"
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define i32 @safe_div(i32* %n, i32* %d) {
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entry:
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%r = alloca i32, align 4
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invoke void @try_body(i32* %r, i32* %n, i32* %d)
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to label %__try.cont unwind label %lpad
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lpad:
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%vals = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @__C_specific_handler to i8*)
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catch i8* bitcast (i32 (i8*, i8*)* @safe_div_filt0 to i8*)
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catch i8* bitcast (i32 (i8*, i8*)* @safe_div_filt1 to i8*)
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%ehptr = extractvalue { i8*, i32 } %vals, 0
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%sel = extractvalue { i8*, i32 } %vals, 1
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%filt0_val = call i32 @llvm.eh.typeid.for(i8* bitcast (i32 (i8*, i8*)* @safe_div_filt0 to i8*))
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%is_filt0 = icmp eq i32 %sel, %filt0_val
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br i1 %is_filt0, label %handler0, label %eh.dispatch1
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eh.dispatch1:
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%filt1_val = call i32 @llvm.eh.typeid.for(i8* bitcast (i32 (i8*, i8*)* @safe_div_filt1 to i8*))
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%is_filt1 = icmp eq i32 %sel, %filt1_val
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br i1 %is_filt1, label %handler1, label %eh.resume
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handler0:
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call void @puts(i8* getelementptr ([27 x i8]* @str1, i32 0, i32 0))
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store i32 -1, i32* %r, align 4
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br label %__try.cont
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handler1:
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call void @puts(i8* getelementptr ([29 x i8]* @str2, i32 0, i32 0))
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store i32 -2, i32* %r, align 4
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br label %__try.cont
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eh.resume:
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resume { i8*, i32 } %vals
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__try.cont:
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%safe_ret = load i32* %r, align 4
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ret i32 %safe_ret
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}
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; Normal path code
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; CHECK: {{^}}safe_div:
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; CHECK: .seh_proc safe_div
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; CHECK: .seh_handler __C_specific_handler, @unwind, @except
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; CHECK: .Ltmp0:
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; CHECK: leaq [[rloc:.*\(%rsp\)]], %rcx
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; CHECK: callq try_body
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; CHECK-NEXT: .Ltmp1
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; CHECK: .LBB0_7:
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; CHECK: movl [[rloc]], %eax
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; CHECK: retq
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; Landing pad code
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; CHECK: .Ltmp3:
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; CHECK: movl $1, %[[sel:[a-z]+]]
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; CHECK: .Ltmp4
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; CHECK: movl $2, %[[sel]]
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; CHECK: .L{{.*}}:
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; CHECK: cmpl $1, %[[sel]]
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; CHECK: # %handler0
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; CHECK: callq puts
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; CHECK: movl $-1, [[rloc]]
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; CHECK: jmp .LBB0_7
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; CHECK: cmpl $2, %[[sel]]
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; CHECK: # %handler1
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; CHECK: callq puts
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; CHECK: movl $-2, [[rloc]]
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; CHECK: jmp .LBB0_7
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; FIXME: EH preparation should not call _Unwind_Resume.
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; CHECK: callq _Unwind_Resume
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; CHECK: ud2
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; CHECK: .seh_handlerdata
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; CHECK: .long 2
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; CHECK: .long .Ltmp0@IMGREL
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; CHECK: .long .Ltmp1@IMGREL+1
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; CHECK: .long safe_div_filt0@IMGREL
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; CHECK: .long .Ltmp3@IMGREL
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; CHECK: .long .Ltmp0@IMGREL
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; CHECK: .long .Ltmp1@IMGREL+1
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; CHECK: .long safe_div_filt1@IMGREL
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; CHECK: .long .Ltmp4@IMGREL
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; CHECK: .text
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; CHECK: .seh_endproc
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define void @try_body(i32* %r, i32* %n, i32* %d) {
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entry:
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%0 = load i32* %n, align 4
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%1 = load i32* %d, align 4
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%div = sdiv i32 %0, %1
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store i32 %div, i32* %r, align 4
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ret void
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}
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; The prototype of these filter functions is:
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; int filter(EXCEPTION_POINTERS *eh_ptrs, void *rbp);
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; The definition of EXCEPTION_POINTERS is:
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; typedef struct _EXCEPTION_POINTERS {
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; EXCEPTION_RECORD *ExceptionRecord;
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; CONTEXT *ContextRecord;
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; } EXCEPTION_POINTERS;
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; The definition of EXCEPTION_RECORD is:
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; typedef struct _EXCEPTION_RECORD {
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; DWORD ExceptionCode;
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; ...
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; } EXCEPTION_RECORD;
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; The exception code can be retreived with two loads, one for the record
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; pointer and one for the code. The values of local variables can be
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; accessed via rbp, but that would require additional not yet implemented LLVM
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; support.
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define i32 @safe_div_filt0(i8* %eh_ptrs, i8* %rbp) {
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%eh_ptrs_c = bitcast i8* %eh_ptrs to i32**
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%eh_rec = load i32** %eh_ptrs_c
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%eh_code = load i32* %eh_rec
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; EXCEPTION_ACCESS_VIOLATION = 0xC0000005
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%cmp = icmp eq i32 %eh_code, 3221225477
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%filt.res = zext i1 %cmp to i32
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ret i32 %filt.res
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}
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define i32 @safe_div_filt1(i8* %eh_ptrs, i8* %rbp) {
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%eh_ptrs_c = bitcast i8* %eh_ptrs to i32**
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%eh_rec = load i32** %eh_ptrs_c
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%eh_code = load i32* %eh_rec
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; EXCEPTION_INT_DIVIDE_BY_ZERO = 0xC0000094
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%cmp = icmp eq i32 %eh_code, 3221225620
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%filt.res = zext i1 %cmp to i32
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ret i32 %filt.res
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}
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@str_result = internal constant [21 x i8] c"safe_div result: %d\0A\00"
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define i32 @main() {
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%d.addr = alloca i32, align 4
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%n.addr = alloca i32, align 4
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store i32 10, i32* %n.addr, align 4
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store i32 2, i32* %d.addr, align 4
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%r1 = call i32 @safe_div(i32* %n.addr, i32* %d.addr)
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call void (i8*, ...)* @printf(i8* getelementptr ([21 x i8]* @str_result, i32 0, i32 0), i32 %r1)
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store i32 10, i32* %n.addr, align 4
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store i32 0, i32* %d.addr, align 4
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%r2 = call i32 @safe_div(i32* %n.addr, i32* %d.addr)
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call void (i8*, ...)* @printf(i8* getelementptr ([21 x i8]* @str_result, i32 0, i32 0), i32 %r2)
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%r3 = call i32 @safe_div(i32* %n.addr, i32* null)
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call void (i8*, ...)* @printf(i8* getelementptr ([21 x i8]* @str_result, i32 0, i32 0), i32 %r3)
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ret i32 0
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}
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define void @_Unwind_Resume() {
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call void @abort()
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unreachable
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}
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declare i32 @__C_specific_handler(...)
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declare i32 @llvm.eh.typeid.for(i8*) readnone nounwind
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declare void @puts(i8*)
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declare void @printf(i8*, ...)
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declare void @abort()
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