Add asm.js-style setjmp/longjmp handling for wasm

Summary: This patch adds asm.js-style setjmp/longjmp handling support for WebAssembly. It also uses JavaScript's try and catch mechanism.

Reviewers: jpp, dschuff

Subscribers: jfb, dschuff

Differential Revision: https://reviews.llvm.org/D23928

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280302 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/WebAssembly/LLVMBuild.txt

@@ -29,5 +29,5 @@ has_disassembler = 1
 type = Library
 name = WebAssemblyCodeGen
 parent = WebAssembly
-required_libraries = Analysis AsmPrinter CodeGen Core MC Scalar SelectionDAG Support Target WebAssemblyAsmPrinter WebAssemblyDesc WebAssemblyInfo
+required_libraries = Analysis AsmPrinter CodeGen Core MC Scalar SelectionDAG Support Target TransformUtils WebAssemblyAsmPrinter WebAssemblyDesc WebAssemblyInfo
 add_to_library_groups = WebAssembly

lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp

@@ -165,7 +165,14 @@ void WebAssemblyPassConfig::addIRPasses() {
   if (getOptLevel() != CodeGenOpt::None)
     addPass(createWebAssemblyOptimizeReturned());
 
-  // Handle exceptions.
+  // If exception handling is not enabled, we lower invokes into calls and
+  // simplify CFG to delete unreachable landingpad blocks.
+  if (!EnableEmException) {
+    addPass(createLowerInvokePass());
+    addPass(createCFGSimplificationPass());
+  }
+
+  // Handle exceptions and setjmp/longjmp if enabled.
   if (EnableEmException || EnableEmSjLj)
     addPass(createWebAssemblyLowerEmscriptenEHSjLj(EnableEmException,
                                                    EnableEmSjLj));

test/CodeGen/WebAssembly/lower-em-ehsjlj-options.ll

@@ -0,0 +1,61 @@
+; RUN: llc < %s -enable-emscripten-cxx-exceptions | FileCheck %s --check-prefix=EH
+; RUN: llc < %s -enable-emscripten-sjlj | FileCheck %s --check-prefix=SJLJ
+; RUN: llc < %s | FileCheck %s --check-prefix=NONE
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown"
+
+%struct.__jmp_buf_tag = type { [6 x i32], i32, [32 x i32] }
+
+define hidden void @exception() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
+; EH-LABEL:   type exception,@function
+; NONE-LABEL: type exception,@function
+entry:
+  invoke void @foo()
+          to label %try.cont unwind label %lpad
+; EH:   call __invoke_void@FUNCTION
+; NONE: call foo@FUNCTION
+
+lpad:                                             ; preds = %entry
+  %0 = landingpad { i8*, i32 }
+          catch i8* null
+  %1 = extractvalue { i8*, i32 } %0, 0
+  %2 = extractvalue { i8*, i32 } %0, 1
+  %3 = call i8* @__cxa_begin_catch(i8* %1) #2
+  call void @__cxa_end_catch()
+  br label %try.cont
+
+try.cont:                                         ; preds = %entry, %lpad
+  ret void
+}
+
+define hidden void @setjmp_longjmp() {
+; SJLJ-LABEL: type setjmp_longjmp,@function
+; NONE-LABEL: type setjmp_longjmp,@function
+entry:
+  %buf = alloca [1 x %struct.__jmp_buf_tag], align 16
+  %arraydecay = getelementptr inbounds [1 x %struct.__jmp_buf_tag], [1 x %struct.__jmp_buf_tag]* %buf, i32 0, i32 0
+  %call = call i32 @setjmp(%struct.__jmp_buf_tag* %arraydecay) #0
+  %arraydecay1 = getelementptr inbounds [1 x %struct.__jmp_buf_tag], [1 x %struct.__jmp_buf_tag]* %buf, i32 0, i32 0
+  call void @longjmp(%struct.__jmp_buf_tag* %arraydecay1, i32 1) #1
+  unreachable
+; SJLJ: i32.call ${{[a-zA-Z0-9]+}}=, saveSetjmp@FUNCTION
+; SJLJ: i32.call ${{[a-zA-Z0-9]+}}=, testSetjmp@FUNCTION
+; NONE: i32.call ${{[a-zA-Z0-9]+}}=, setjmp@FUNCTION
+; NONE: call longjmp@FUNCTION
+}
+
+declare void @foo()
+declare i32 @__gxx_personality_v0(...)
+declare i8* @__cxa_begin_catch(i8*)
+declare void @__cxa_end_catch()
+; Function Attrs: returns_twice
+declare i32 @setjmp(%struct.__jmp_buf_tag*) #0
+; Function Attrs: noreturn
+declare void @longjmp(%struct.__jmp_buf_tag*, i32) #1
+declare i8* @malloc(i32)
+declare void @free(i8*)
+
+attributes #0 = { returns_twice }
+attributes #1 = { noreturn }
+attributes #2 = { nounwind }

test/CodeGen/WebAssembly/lower-em-exceptions-whitelist.ll

@@ -1,5 +1,8 @@
 ; RUN: opt < %s -wasm-lower-em-ehsjlj -emscripten-cxx-exceptions-whitelist=do_catch -S | FileCheck %s
 
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown"
+
 define void @dont_catch() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
 ; CHECK-LABEL: @dont_catch(
 entry:
@@ -34,7 +37,7 @@ entry:
   invoke void @foo()
           to label %invoke.cont unwind label %lpad
 ; CHECK: entry:
-; CHECK-NEXT: store i1 false, i1*
+; CHECK-NEXT: store i32 0, i32*
 ; CHECK-NEXT: call void @__invoke_void(void ()* @foo)
 
 invoke.cont:                                      ; preds = %entry

test/CodeGen/WebAssembly/lower-em-exceptions.ll

@@ -1,10 +1,13 @@
 ; RUN: opt < %s -wasm-lower-em-ehsjlj -S | FileCheck %s
 
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown"
+
 @_ZTIi = external constant i8*
 @_ZTIc = external constant i8*
-; CHECK: @[[__THREW__:__THREW__.*]] = global i1 false
-; CHECK: @[[THREWVALUE:__threwValue.*]] = global i32 0
-; CHECK: @[[TEMPRET0:__tempRet0.*]] = global i32 0
+; CHECK-DAG: @[[__THREW__:__THREW__.*]] = global i32 0
+; CHECK-DAG: @[[THREWVALUE:__threwValue.*]] = global i32 0
+; CHECK-DAG: @[[TEMPRET0:__tempRet0.*]] = global i32 0
 
 ; Test invoke instruction with clauses (try-catch block)
 define void @clause() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
@@ -13,11 +16,12 @@ entry:
   invoke void @foo(i32 3)
           to label %invoke.cont unwind label %lpad
 ; CHECK: entry:
-; CHECK-NEXT: store i1 false, i1* @[[__THREW__]]
+; CHECK-NEXT: store i32 0, i32* @[[__THREW__]]
 ; CHECK-NEXT: call void @__invoke_void_i32(void (i32)* @foo, i32 3)
-; CHECK-NEXT: %[[__THREW__VAL:.*]] = load i1, i1* @[[__THREW__]]
-; CHECK-NEXT: store i1 false, i1* @[[__THREW__]]
-; CHECK-NEXT: br i1 %[[__THREW__VAL]], label %lpad, label %invoke.cont
+; CHECK-NEXT: %[[__THREW__VAL:.*]] = load i32, i32* @[[__THREW__]]
+; CHECK-NEXT: store i32 0, i32* @[[__THREW__]]
+; CHECK-NEXT: %cmp = icmp eq i32 %[[__THREW__VAL]], 1
+; CHECK-NEXT: br i1 %cmp, label %lpad, label %invoke.cont
 
 invoke.cont:                                      ; preds = %entry
   br label %try.cont
@@ -68,11 +72,12 @@ entry:
   invoke void @foo(i32 3)
           to label %invoke.cont unwind label %lpad
 ; CHECK: entry:
-; CHECK-NEXT: store i1 false, i1* @[[__THREW__]]
+; CHECK-NEXT: store i32 0, i32* @[[__THREW__]]
 ; CHECK-NEXT: call void @__invoke_void_i32(void (i32)* @foo, i32 3)
-; CHECK-NEXT: %[[__THREW__VAL:.*]] = load i1, i1* @[[__THREW__]]
-; CHECK-NEXT: store i1 false, i1* @[[__THREW__]]
-; CHECK-NEXT: br i1 %[[__THREW__VAL]], label %lpad, label %invoke.cont
+; CHECK-NEXT: %[[__THREW__VAL:.*]] = load i32, i32* @[[__THREW__]]
+; CHECK-NEXT: store i32 0, i32* @[[__THREW__]]
+; CHECK-NEXT: %cmp = icmp eq i32 %[[__THREW__VAL]], 1
+; CHECK-NEXT: br i1 %cmp, label %lpad, label %invoke.cont
 
 invoke.cont:                                      ; preds = %entry
   ret void
@@ -118,7 +123,7 @@ entry:
   %0 = invoke noalias i8* @bar(i8 signext 1, i8 zeroext 2)
           to label %invoke.cont unwind label %lpad
 ; CHECK: entry:
-; CHECK-NEXT: store i1 false, i1* @[[__THREW__]]
+; CHECK-NEXT: store i32 0, i32* @[[__THREW__]]
 ; CHECK-NEXT: %0 = call noalias i8* @"__invoke_i8*_i8_i8"(i8* (i8, i8)* @bar, i8 signext 1, i8 zeroext 2)
 
 invoke.cont:                                      ; preds = %entry
@@ -162,19 +167,19 @@ declare i8* @__cxa_begin_catch(i8*)
 declare void @__cxa_end_catch()
 declare void @__cxa_call_unexpected(i8*)
 
-; JS glue functions and invoke wrappers registration
-; CHECK: declare void @__resumeException(i8*)
-; CHECK: declare void @__invoke_void_i32(void (i32)*, i32)
-; CHECK: declare i8* @__cxa_find_matching_catch_4(i8*, i8*)
+; JS glue functions and invoke wrappers declaration
+; CHECK-DAG: declare void @__resumeException(i8*)
+; CHECK-DAG: declare void @__invoke_void_i32(void (i32)*, i32)
+; CHECK-DAG: declare i8* @__cxa_find_matching_catch_4(i8*, i8*)
 
 ; setThrew function creation
-; CHECK-LABEL: define void @setThrew(i1 %threw, i32 %value) {
+; CHECK-LABEL: define void @setThrew(i32 %threw, i32 %value) {
 ; CHECK: entry:
-; CHECK-NEXT: %[[__THREW__]].val = load i1, i1* @[[__THREW__]]
-; CHECK-NEXT: %cmp = icmp eq i1 %[[__THREW__]].val, false
+; CHECK-NEXT: %[[__THREW__]].val = load i32, i32* @[[__THREW__]]
+; CHECK-NEXT: %cmp = icmp eq i32 %[[__THREW__]].val, 0
 ; CHECK-NEXT: br i1 %cmp, label %if.then, label %if.end
 ; CHECK: if.then:
-; CHECK-NEXT: store i1 %threw, i1* @[[__THREW__]]
+; CHECK-NEXT: store i32 %threw, i32* @[[__THREW__]]
 ; CHECK-NEXT: store i32 %value, i32* @[[THREWVALUE]]
 ; CHECK-NEXT: br label %if.end
 ; CHECK: if.end: