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Memory size from emcc #4

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kripken opened this issue Nov 13, 2015 · 1 comment
Closed

Memory size from emcc #4

kripken opened this issue Nov 13, 2015 · 1 comment

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@kripken
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kripken commented Nov 13, 2015

We need to pass the memory size info from emscripten to the memory section of the wasm module. Perhaps we should parse it out of the js file?

@kripken
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kripken commented Dec 17, 2015

Done in wasm.js.

@kripken kripken closed this as completed Dec 17, 2015
@sletz sletz mentioned this issue Jan 4, 2016
aheejin added a commit to aheejin/binaryen that referenced this issue Feb 17, 2021
We decided to change `catch_all`'s opcode from 0x05, which is the same
as `else`, to 0x19, to avoid some complicated handling in the tools.

See: WebAssembly/exception-handling#147

---

dwarf_with_exceptions.wasm was added in WebAssembly#3496 but we didn't comment on
how that file was created, so I'll add some comment on that here, in
case we need to regenerate this file with some modifications. I
regenerated dwarf_with_exceptions.wasm, so some variable names and such
have changed.

cpp file:
```cpp
void foo();

void test_debuginfo() {
  try {
    foo();
  } catch (...) {
    foo();
  }
}
```

Run:
```
$ clang++ -std=c++14 -stdlib=libc++ --target=wasm32-unknown-unknown -fwasm-exceptions -Xclang -disable-O0-optnone -c -S -emit-llvm test_debuginfo.cpp -o temp.ll
$ opt -S -mem2reg -simplifycfg temp.ll -o test_debuginfo.ll
```
(`opt -mem2reg -simplifycfg` was run to make the code little tidier.
This basically promotes stack loads/saves to registers and simplifies
the CFG.)

Resulting ll file, after modifying some function names and removing
personal info in directory names:
```llvm
source_filename = "test_debuginfo.cpp"
target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
target triple = "wasm32-unknown-unknown"

$__clang_call_terminate = comdat any

; Function Attrs: noinline mustprogress
define hidden void @test_debuginfo() #0 personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) !dbg !7 {
entry:
  invoke void @foo()
          to label %try.cont unwind label %catch.dispatch, !dbg !10

catch.dispatch:                                   ; preds = %entry
  %0 = catchswitch within none [label %catch.start] unwind to caller, !dbg !12

catch.start:                                      ; preds = %catch.dispatch
  %1 = catchpad within %0 [i8* null], !dbg !12
  %2 = call i8* @llvm.wasm.get.exception(token %1), !dbg !12
  %3 = call i32 @llvm.wasm.get.ehselector(token %1), !dbg !12
  %4 = call i8* @__cxa_begin_catch(i8* %2) WebAssembly#2 [ "funclet"(token %1) ], !dbg !12
  invoke void @foo() [ "funclet"(token %1) ]
          to label %invoke.cont1 unwind label %ehcleanup, !dbg !13

invoke.cont1:                                     ; preds = %catch.start
  call void @__cxa_end_catch() [ "funclet"(token %1) ], !dbg !15
  catchret from %1 to label %try.cont, !dbg !15

try.cont:                                         ; preds = %entry, %invoke.cont1
  ret void, !dbg !16

ehcleanup:                                        ; preds = %catch.start
  %5 = cleanuppad within %1 [], !dbg !15
  invoke void @__cxa_end_catch() [ "funclet"(token %5) ]
          to label %invoke.cont2 unwind label %terminate, !dbg !15

invoke.cont2:                                     ; preds = %ehcleanup
  cleanupret from %5 unwind to caller, !dbg !15

terminate:                                        ; preds = %ehcleanup
  %6 = cleanuppad within %5 [], !dbg !15
  %7 = call i8* @llvm.wasm.get.exception(token %6), !dbg !15
  call void @__clang_call_terminate(i8* %7) WebAssembly#5 [ "funclet"(token %6) ], !dbg !15
  unreachable, !dbg !15
}

declare void @foo() WebAssembly#1

declare i32 @__gxx_wasm_personality_v0(...)

; Function Attrs: nounwind
declare i8* @llvm.wasm.get.exception(token) WebAssembly#2

; Function Attrs: nounwind
declare i32 @llvm.wasm.get.ehselector(token) WebAssembly#2

; Function Attrs: nounwind readnone
declare i32 @llvm.eh.typeid.for(i8*) WebAssembly#3

declare i8* @__cxa_begin_catch(i8*)

declare void @__cxa_end_catch()

; Function Attrs: noinline noreturn nounwind
define linkonce_odr hidden void @__clang_call_terminate(i8* %0) WebAssembly#4 comdat {
  %2 = call i8* @__cxa_begin_catch(i8* %0) WebAssembly#2
  call void @_ZSt9terminatev() WebAssembly#5
  unreachable
}

declare void @_ZSt9terminatev()

attributes #0 = { noinline mustprogress "disable-tail-calls"="false" "frame-pointer"="none" "min-legal-vector-width"="0" "no-jump-tables"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="generic" "target-features"="+exception-handling" }
attributes WebAssembly#1 = { "disable-tail-calls"="false" "frame-pointer"="none" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="generic" "target-features"="+exception-handling" }
attributes WebAssembly#2 = { nounwind }
attributes WebAssembly#3 = { nounwind readnone }
attributes WebAssembly#4 = { noinline noreturn nounwind }
attributes WebAssembly#5 = { noreturn nounwind }

!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4, !5}
!llvm.ident = !{!6}

!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 13.0.0 (https://github.com/llvm/llvm-project.git 3c4c205060c9398da705eb71b63ddd8a04999de9)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
!1 = !DIFile(filename: "test_debuginfo.cpp", directory: "/")
!2 = !{}
!3 = !{i32 7, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = !{i32 1, !"wchar_size", i32 4}
!6 = !{!"clang version 13.0.0 (https://github.com/llvm/llvm-project.git 3c4c205060c9398da705eb71b63ddd8a04999de9)"}
!7 = distinct !DISubprogram(name: "test_debuginfo", linkageName: "test_debuginfo", scope: !1, file: !1, line: 3, type: !8, scopeLine: 3, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
!8 = !DISubroutineType(types: !9)
!9 = !{null}
!10 = !DILocation(line: 5, column: 5, scope: !11)
!11 = distinct !DILexicalBlock(scope: !7, file: !1, line: 4, column: 7)
!12 = !DILocation(line: 6, column: 3, scope: !11)
!13 = !DILocation(line: 7, column: 5, scope: !14)
!14 = distinct !DILexicalBlock(scope: !7, file: !1, line: 6, column: 17)
!15 = !DILocation(line: 8, column: 3, scope: !14)
!16 = !DILocation(line: 9, column: 1, scope: !7)
```

Run:
```
llc -exception-model=wasm -mattr=+exception-handling -filetype=obj test_debuginfo.ll -o test_debuginfo.o
wasm-ld --no-entry --no-gc-sections --allow-undefined test_debuginfo.o -o test_debuginfo.wasm
```
aheejin added a commit to aheejin/binaryen that referenced this issue Feb 17, 2021
We decided to change `catch_all`'s opcode from 0x05, which is the same
as `else`, to 0x19, to avoid some complicated handling in the tools.

See: WebAssembly/exception-handling#147

---

dwarf_with_exceptions.wasm was added in WebAssembly#3496 but we didn't comment on
how that file was created, so I'll add some comment on that here, in
case we need to regenerate this file with some modifications. I
regenerated dwarf_with_exceptions.wasm, so some variable names and such
have changed.

cpp file:
```cpp
void foo();

void test_debuginfo() {
  try {
    foo();
  } catch (...) {
    foo();
  }
}
```

Run:
```
$ clang++ -std=c++14 -stdlib=libc++ --target=wasm32-unknown-unknown -fwasm-exceptions -Xclang -disable-O0-optnone -c -S -emit-llvm test_debuginfo.cpp -o temp.ll
$ opt -S -mem2reg -simplifycfg temp.ll -o test_debuginfo.ll
```
(`opt -mem2reg -simplifycfg` was run to make the code little tidier.
This basically promotes stack loads/saves to registers and simplifies
the CFG.)

Resulting ll file, after modifying some function names and removing
personal info in directory names:
```llvm
source_filename = "test_debuginfo.cpp"
target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
target triple = "wasm32-unknown-unknown"

$__clang_call_terminate = comdat any

; Function Attrs: noinline mustprogress
define hidden void @test_debuginfo() #0 personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) !dbg !7 {
entry:
  invoke void @foo()
          to label %try.cont unwind label %catch.dispatch, !dbg !10

catch.dispatch:                                   ; preds = %entry
  %0 = catchswitch within none [label %catch.start] unwind to caller, !dbg !12

catch.start:                                      ; preds = %catch.dispatch
  %1 = catchpad within %0 [i8* null], !dbg !12
  %2 = call i8* @llvm.wasm.get.exception(token %1), !dbg !12
  %3 = call i32 @llvm.wasm.get.ehselector(token %1), !dbg !12
  %4 = call i8* @__cxa_begin_catch(i8* %2) WebAssembly#2 [ "funclet"(token %1) ], !dbg !12
  invoke void @foo() [ "funclet"(token %1) ]
          to label %invoke.cont1 unwind label %ehcleanup, !dbg !13

invoke.cont1:                                     ; preds = %catch.start
  call void @__cxa_end_catch() [ "funclet"(token %1) ], !dbg !15
  catchret from %1 to label %try.cont, !dbg !15

try.cont:                                         ; preds = %entry, %invoke.cont1
  ret void, !dbg !16

ehcleanup:                                        ; preds = %catch.start
  %5 = cleanuppad within %1 [], !dbg !15
  invoke void @__cxa_end_catch() [ "funclet"(token %5) ]
          to label %invoke.cont2 unwind label %terminate, !dbg !15

invoke.cont2:                                     ; preds = %ehcleanup
  cleanupret from %5 unwind to caller, !dbg !15

terminate:                                        ; preds = %ehcleanup
  %6 = cleanuppad within %5 [], !dbg !15
  %7 = call i8* @llvm.wasm.get.exception(token %6), !dbg !15
  call void @__clang_call_terminate(i8* %7) WebAssembly#5 [ "funclet"(token %6) ], !dbg !15
  unreachable, !dbg !15
}

declare void @foo() WebAssembly#1

declare i32 @__gxx_wasm_personality_v0(...)

; Function Attrs: nounwind
declare i8* @llvm.wasm.get.exception(token) WebAssembly#2

; Function Attrs: nounwind
declare i32 @llvm.wasm.get.ehselector(token) WebAssembly#2

; Function Attrs: nounwind readnone
declare i32 @llvm.eh.typeid.for(i8*) WebAssembly#3

declare i8* @__cxa_begin_catch(i8*)

declare void @__cxa_end_catch()

; Function Attrs: noinline noreturn nounwind
define linkonce_odr hidden void @__clang_call_terminate(i8* %0) WebAssembly#4 comdat {
  %2 = call i8* @__cxa_begin_catch(i8* %0) WebAssembly#2
  call void @_ZSt9terminatev() WebAssembly#5
  unreachable
}

declare void @_ZSt9terminatev()

attributes #0 = { noinline mustprogress "disable-tail-calls"="false" "frame-pointer"="none" "min-legal-vector-width"="0" "no-jump-tables"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="generic" "target-features"="+exception-handling" }
attributes WebAssembly#1 = { "disable-tail-calls"="false" "frame-pointer"="none" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="generic" "target-features"="+exception-handling" }
attributes WebAssembly#2 = { nounwind }
attributes WebAssembly#3 = { nounwind readnone }
attributes WebAssembly#4 = { noinline noreturn nounwind }
attributes WebAssembly#5 = { noreturn nounwind }

!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4, !5}
!llvm.ident = !{!6}

!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 13.0.0 (https://github.com/llvm/llvm-project.git 3c4c205060c9398da705eb71b63ddd8a04999de9)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
!1 = !DIFile(filename: "test_debuginfo.cpp", directory: "/")
!2 = !{}
!3 = !{i32 7, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = !{i32 1, !"wchar_size", i32 4}
!6 = !{!"clang version 13.0.0 (https://github.com/llvm/llvm-project.git 3c4c205060c9398da705eb71b63ddd8a04999de9)"}
!7 = distinct !DISubprogram(name: "test_debuginfo", linkageName: "test_debuginfo", scope: !1, file: !1, line: 3, type: !8, scopeLine: 3, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
!8 = !DISubroutineType(types: !9)
!9 = !{null}
!10 = !DILocation(line: 5, column: 5, scope: !11)
!11 = distinct !DILexicalBlock(scope: !7, file: !1, line: 4, column: 7)
!12 = !DILocation(line: 6, column: 3, scope: !11)
!13 = !DILocation(line: 7, column: 5, scope: !14)
!14 = distinct !DILexicalBlock(scope: !7, file: !1, line: 6, column: 17)
!15 = !DILocation(line: 8, column: 3, scope: !14)
!16 = !DILocation(line: 9, column: 1, scope: !7)
```

Run:
```
$ llc -exception-model=wasm -mattr=+exception-handling -filetype=obj test_debuginfo.ll -o test_debuginfo.o
$ wasm-ld --no-entry --no-gc-sections --allow-undefined test_debuginfo.o -o test_debuginfo.wasm
```
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