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clang-p2996/llvm/test/CodeGen/WebAssembly/eh-lsda.ll
Heejin Ahn 9261ee32dc [WebAssembly] Make EH work with dynamic linking 
This makes Wasm EH work with dynamic linking. So far we were only able
to handle destructors, which do not use any tags or LSDA info.

1. This uses `TargetExternalSymbol` for `GCC_except_tableN` symbols,
   which points to the address of per-function LSDA info. It is more
   convenient to use than `MCSymbol` because it can take additional
   target flags.

2. When lowering `wasm_lsda` intrinsic, if PIC is enabled, make the
   symbol relative to `__memory_base` and generate the `add` node. If
   PIC is disabled, continue to use the absolute address.

3. Make tag symbols (`__cpp_exception` and `__c_longjmp`) undefined in
   the backend, because it is hard to make it work with dynamic
   linking's loading order. Instead, we make all tag symbols undefined
   in the LLVM backend and import it from JS.

4. Add support for undefined tags to the linker.

Companion patches:
- https://github.com/WebAssembly/binaryen/pull/4223
- https://github.com/emscripten-core/emscripten/pull/15266

Reviewed By: sbc100

Differential Revision: https://reviews.llvm.org/D111388
2021-10-12 23:28:27 -07:00

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; RUN: llc < %s --mtriple=wasm32-unknown-unknown -wasm-disable-explicit-locals -wasm-keep-registers -wasm-enable-eh -exception-model=wasm -mattr=+exception-handling | FileCheck %s -check-prefixes=CHECK,NOPIC -DPTR=32
; RUN: llc < %s --mtriple=wasm64-unknown-unknown -wasm-disable-explicit-locals -wasm-keep-registers -wasm-enable-eh -exception-model=wasm -mattr=+exception-handling | FileCheck %s -check-prefixes=CHECK,NOPIC -DPTR=64
; RUN: llc < %s --mtriple=wasm32-unknown-emscripten -wasm-disable-explicit-locals -wasm-keep-registers -wasm-enable-eh -exception-model=wasm -mattr=+exception-handling | FileCheck %s -check-prefixes=CHECK,NOPIC -DPTR=32
; RUN: llc < %s --mtriple=wasm64-unknown-emscripten -wasm-disable-explicit-locals -wasm-keep-registers -wasm-enable-eh -exception-model=wasm -mattr=+exception-handling | FileCheck %s -check-prefixes=CHECK,NOPIC -DPTR=64
; RUN: llc < %s --mtriple=wasm32-unknown-emscripten -wasm-disable-explicit-locals -wasm-keep-registers -wasm-enable-eh -exception-model=wasm -mattr=+exception-handling -relocation-model=pic | FileCheck %s -check-prefixes=CHECK,PIC -DPTR=32
; RUN: llc < %s --mtriple=wasm64-unknown-emscripten -wasm-disable-explicit-locals -wasm-keep-registers -wasm-enable-eh -exception-model=wasm -mattr=+exception-handling -relocation-model=pic | FileCheck %s -check-prefixes=CHECK,PIC -DPTR=64
@_ZTIi = external constant i8*
@_ZTIf = external constant i8*
@_ZTId = external constant i8*
; Single catch (...) does not need an exception table.
;
; try {
; may_throw();
; } catch (...) {
; }
; CHECK-LABEL: test0:
; CHECK-NOT: GCC_except_table
define void @test0() personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) {
entry:
invoke void @may_throw()
to label %try.cont unwind label %catch.dispatch
catch.dispatch: ; preds = %entry
%0 = catchswitch within none [label %catch.start] unwind to caller
catch.start: ; preds = %catch.dispatch
%1 = catchpad within %0 [i8* null]
%2 = call i8* @llvm.wasm.get.exception(token %1)
%3 = call i32 @llvm.wasm.get.ehselector(token %1)
%4 = call i8* @__cxa_begin_catch(i8* %2) [ "funclet"(token %1) ]
call void @__cxa_end_catch() [ "funclet"(token %1) ]
catchret from %1 to label %try.cont
try.cont: ; preds = %entry, %catch.start
ret void
}
; Exception table generation + shared action test.
;
; try {
; may_throw();
; } catch (int) {
; } catch (float) {
; } catch (double) {
; } catch (...) {
; }
;
; try {
; may_throw();
; } catch (double) {
; } catch (...) {
; }
;
; try {
; may_throw();
; } catch (int) {
; } catch (float) {
; }
;
; There are three landing pads. The second landing pad should share action table
; entries with the first landing pad because they end with the same sequence
; (double -> ...). But the third landing table cannot share action table entries
; with others, so it should create its own entries.
; CHECK-LABEL: test1:
; In static linking, we load GCC_except_table as a constant directly.
; NOPIC: i[[PTR]].const $push[[CONTEXT:.*]]=, __wasm_lpad_context
; NOPIC-NEXT: i[[PTR]].const $push[[EXCEPT_TABLE:.*]]=, GCC_except_table1
; NOPIC-NEXT: i[[PTR]].store {{[48]}}($pop[[CONTEXT]]), $pop[[EXCEPT_TABLE]]
; In case of PIC, we make GCC_except_table symbols a relative on based on
; __memory_base.
; PIC: global.get $push[[CONTEXT:.*]]=, __wasm_lpad_context@GOT
; PIC-NEXT: local.tee $push{{.*}}=, $[[CONTEXT_LOCAL:.*]]=, $pop[[CONTEXT]]
; PIC: global.get $push[[MEMORY_BASE:.*]]=, __memory_base
; PIC-NEXT: i[[PTR]].const $push[[EXCEPT_TABLE_REL:.*]]=, GCC_except_table1@MBREL
; PIC-NEXT: i[[PTR]].add $push[[EXCEPT_TABLE:.*]]=, $pop[[MEMORY_BASE]], $pop[[EXCEPT_TABLE_REL]]
; PIC-NEXT: i[[PTR]].store {{[48]}}($[[CONTEXT_LOCAL]]), $pop[[EXCEPT_TABLE]]
; CHECK: .section .rodata.gcc_except_table,"",@
; CHECK-NEXT: .p2align 2
; CHECK-NEXT: GCC_except_table[[START:[0-9]+]]:
; CHECK-NEXT: .Lexception0:
; CHECK-NEXT: .int8 255 # @LPStart Encoding = omit
; CHECK-NEXT: .int8 0 # @TType Encoding = absptr
; CHECK-NEXT: .uleb128 .Lttbase0-.Lttbaseref0
; CHECK-NEXT: .Lttbaseref0:
; CHECK-NEXT: .int8 1 # Call site Encoding = uleb128
; CHECK-NEXT: .uleb128 .Lcst_end0-.Lcst_begin0
; CHECK-NEXT: .Lcst_begin0:
; CHECK-NEXT: .int8 0 # >> Call Site 0 <<
; CHECK-NEXT: # On exception at call site 0
; CHECK-NEXT: .int8 7 # Action: 4
; CHECK-NEXT: .int8 1 # >> Call Site 1 <<
; CHECK-NEXT: # On exception at call site 1
; CHECK-NEXT: .int8 3 # Action: 2
; CHECK-NEXT: .int8 2 # >> Call Site 2 <<
; CHECK-NEXT: # On exception at call site 2
; CHECK-NEXT: .int8 11 # Action: 6
; CHECK-NEXT: .Lcst_end0:
; CHECK-NEXT: .int8 1 # >> Action Record 1 <<
; CHECK-NEXT: # Catch TypeInfo 1
; CHECK-NEXT: .int8 0 # No further actions
; CHECK-NEXT: .int8 2 # >> Action Record 2 <<
; CHECK-NEXT: # Catch TypeInfo 2
; CHECK-NEXT: .int8 125 # Continue to action 1
; CHECK-NEXT: .int8 3 # >> Action Record 3 <<
; CHECK-NEXT: # Catch TypeInfo 3
; CHECK-NEXT: .int8 125 # Continue to action 2
; CHECK-NEXT: .int8 4 # >> Action Record 4 <<
; CHECK-NEXT: # Catch TypeInfo 4
; CHECK-NEXT: .int8 125 # Continue to action 3
; CHECK-NEXT: .int8 3 # >> Action Record 5 <<
; CHECK-NEXT: # Catch TypeInfo 3
; CHECK-NEXT: .int8 0 # No further actions
; CHECK-NEXT: .int8 4 # >> Action Record 6 <<
; CHECK-NEXT: # Catch TypeInfo 4
; CHECK-NEXT: .int8 125 # Continue to action 5
; CHECK-NEXT: .p2align 2
; CHECK-NEXT: # >> Catch TypeInfos <<
; CHECK-NEXT: .int[[PTR]] _ZTIi # TypeInfo 4
; CHECK-NEXT: .int[[PTR]] _ZTIf # TypeInfo 3
; CHECK-NEXT: .int[[PTR]] _ZTId # TypeInfo 2
; CHECK-NEXT: .int[[PTR]] 0 # TypeInfo 1
; CHECK-NEXT: .Lttbase0:
; CHECK-NEXT: .p2align 2
; CHECK-NEXT: .LGCC_except_table_end[[END:[0-9]+]]:
; CHECK-NEXT: .size GCC_except_table[[START]], .LGCC_except_table_end[[END]]-GCC_except_table[[START]]
define void @test1() personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) {
entry:
invoke void @may_throw()
to label %try.cont unwind label %catch.dispatch
catch.dispatch: ; preds = %entry
%0 = catchswitch within none [label %catch.start] unwind to caller
catch.start: ; preds = %catch.dispatch
%1 = catchpad within %0 [i8* bitcast (i8** @_ZTIi to i8*), i8* bitcast (i8** @_ZTIf to i8*), i8* bitcast (i8** @_ZTId to i8*), i8* null]
%2 = call i8* @llvm.wasm.get.exception(token %1)
%3 = call i32 @llvm.wasm.get.ehselector(token %1)
%4 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIi to i8*))
%matches = icmp eq i32 %3, %4
br i1 %matches, label %catch10, label %catch.fallthrough
catch10: ; preds = %catch.start
%5 = call i8* @__cxa_begin_catch(i8* %2) [ "funclet"(token %1) ]
%6 = bitcast i8* %5 to i32*
%7 = load i32, i32* %6, align 4
call void @__cxa_end_catch() [ "funclet"(token %1) ]
catchret from %1 to label %try.cont
try.cont: ; preds = %entry, %catch, %catch4, %catch7, %catch10
invoke void @may_throw()
to label %try.cont23 unwind label %catch.dispatch14
catch.dispatch14: ; preds = %try.cont
%8 = catchswitch within none [label %catch.start15] unwind to caller
catch.start15: ; preds = %catch.dispatch14
%9 = catchpad within %8 [i8* bitcast (i8** @_ZTId to i8*), i8* null]
%10 = call i8* @llvm.wasm.get.exception(token %9)
%11 = call i32 @llvm.wasm.get.ehselector(token %9)
%12 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTId to i8*))
%matches16 = icmp eq i32 %11, %12
%13 = call i8* @__cxa_begin_catch(i8* %10) [ "funclet"(token %9) ]
br i1 %matches16, label %catch20, label %catch17
catch20: ; preds = %catch.start15
%14 = bitcast i8* %13 to double*
%15 = load double, double* %14, align 8
call void @__cxa_end_catch() [ "funclet"(token %9) ]
catchret from %9 to label %try.cont23
try.cont23: ; preds = %try.cont, %catch17, %catch20
invoke void @may_throw()
to label %try.cont36 unwind label %catch.dispatch25
catch.dispatch25: ; preds = %try.cont23
%16 = catchswitch within none [label %catch.start26] unwind to caller
catch.start26: ; preds = %catch.dispatch25
%17 = catchpad within %16 [i8* bitcast (i8** @_ZTIi to i8*), i8* bitcast (i8** @_ZTIf to i8*)]
%18 = call i8* @llvm.wasm.get.exception(token %17)
%19 = call i32 @llvm.wasm.get.ehselector(token %17)
%20 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIi to i8*))
%matches27 = icmp eq i32 %19, %20
br i1 %matches27, label %catch33, label %catch.fallthrough28
catch33: ; preds = %catch.start26
%21 = call i8* @__cxa_begin_catch(i8* %18) [ "funclet"(token %17) ]
%22 = bitcast i8* %21 to i32*
%23 = load i32, i32* %22, align 4
call void @__cxa_end_catch() [ "funclet"(token %17) ]
catchret from %17 to label %try.cont36
catch.fallthrough28: ; preds = %catch.start26
%24 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIf to i8*))
%matches29 = icmp eq i32 %19, %24
br i1 %matches29, label %catch30, label %rethrow
catch30: ; preds = %catch.fallthrough28
%25 = call i8* @__cxa_begin_catch(i8* %18) [ "funclet"(token %17) ]
%26 = bitcast i8* %25 to float*
%27 = load float, float* %26, align 4
call void @__cxa_end_catch() [ "funclet"(token %17) ]
catchret from %17 to label %try.cont36
rethrow: ; preds = %catch.fallthrough28
call void @__cxa_rethrow() [ "funclet"(token %17) ]
unreachable
try.cont36: ; preds = %try.cont23, %catch30, %catch33
ret void
catch17: ; preds = %catch.start15
call void @__cxa_end_catch() [ "funclet"(token %9) ]
catchret from %9 to label %try.cont23
catch.fallthrough: ; preds = %catch.start
%28 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIf to i8*))
%matches1 = icmp eq i32 %3, %28
br i1 %matches1, label %catch7, label %catch.fallthrough2
catch7: ; preds = %catch.fallthrough
%29 = call i8* @__cxa_begin_catch(i8* %2) [ "funclet"(token %1) ]
%30 = bitcast i8* %29 to float*
%31 = load float, float* %30, align 4
call void @__cxa_end_catch() [ "funclet"(token %1) ]
catchret from %1 to label %try.cont
catch.fallthrough2: ; preds = %catch.fallthrough
%32 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTId to i8*))
%matches3 = icmp eq i32 %3, %32
%33 = call i8* @__cxa_begin_catch(i8* %2) [ "funclet"(token %1) ]
br i1 %matches3, label %catch4, label %catch
catch4: ; preds = %catch.fallthrough2
%34 = bitcast i8* %33 to double*
%35 = load double, double* %34, align 8
call void @__cxa_end_catch() [ "funclet"(token %1) ]
catchret from %1 to label %try.cont
catch: ; preds = %catch.fallthrough2
call void @__cxa_end_catch() [ "funclet"(token %1) ]
catchret from %1 to label %try.cont
}
declare void @may_throw()
; Function Attrs: nounwind
declare i32 @llvm.eh.typeid.for(i8*) #0
; Function Attrs: nounwind
declare i8* @llvm.wasm.get.exception(token) #0
; Function Attrs: nounwind
declare i32 @llvm.wasm.get.ehselector(token) #0
declare void @__cxa_rethrow()
declare i8* @__cxa_begin_catch(i8*)
declare void @__cxa_end_catch()
declare i32 @__gxx_wasm_personality_v0(...)
attributes #0 = { nounwind }
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