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Add an option for the PostEmscripten pass to set the sbrk ptr location (which is called DYNAMICTOP_PTR in emscripten) #2325

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Merged
kripken merged 2 commits into from
Sep 4, 2019
Merged

Add an option for the PostEmscripten pass to set the sbrk ptr location (which is called DYNAMICTOP_PTR in emscripten) #2325

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6d63106
Add an option for the PostEmscripten pass to set the sbrk ptr locatio…
kripken Sep 2, 2019
0b79ef5
(do nothing if no such function exists, maybe it was dce'd away)
kripken Sep 3, 2019
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31 changes: 29 additions & 2 deletions src/passes/PostEmscripten.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -20,17 +20,21 @@
//

#include <asmjs/shared-constants.h>
#include <ir/import-utils.h>
#include <ir/localize.h>
#include <pass.h>
#include <shared-constants.h>
#include <wasm-builder.h>
#include <wasm.h>

namespace wasm {

struct PostEmscripten : public WalkerPass<PostWalker<PostEmscripten>> {
namespace {

struct OptimizeCalls : public WalkerPass<PostWalker<OptimizeCalls>> {
bool isFunctionParallel() override { return true; }

Pass* create() override { return new PostEmscripten; }
Pass* create() override { return new OptimizeCalls; }

void visitCall(Call* curr) {
// special asm.js imports can be optimized
Expand Down Expand Up @@ -60,6 +64,29 @@ struct PostEmscripten : public WalkerPass<PostWalker<PostEmscripten>> {
}
};

} // namespace

struct PostEmscripten : public Pass {
void run(PassRunner* runner, Module* module) override {
// Apply the sbrk ptr, if it was provided.
auto sbrkPtrStr =
runner->options.getArgumentOrDefault("emscripten-sbrk-ptr", "");
if (sbrkPtrStr != "") {
auto sbrkPtr = std::stoi(sbrkPtrStr);
ImportInfo imports(*module);
auto* func = imports.getImportedFunction(ENV, "emscripten_get_sbrk_ptr");
if (func) {
Builder builder(*module);
func->body = builder.makeConst(Literal(int32_t(sbrkPtr)));
func->module = func->base = Name();
}
}

// Optimize calls
OptimizeCalls().run(runner, module);

@jgravelle-google jgravelle-google Sep 4, 2019

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This feels awkward, but I'm not sure if there's a better way to replace sbrk keeping the order before this

@kripken kripken Sep 4, 2019

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Yeah. I think some of the fastcomp-specific parts can be removed when we remove fastcomp, and then this pass can get simpler again.

}
};

Pass* createPostEmscriptenPass() { return new PostEmscripten(); }

} // namespace wasm
8 changes: 8 additions & 0 deletions test/passes/post-emscripten_pass-arg=emscripten-sbrk-ptr@4008.txt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,8 @@
(module
(type $FUNCSIG$i (func (result i32)))
(func $internal (; 0 ;) (type $FUNCSIG$i) (result i32)
(i32.const 4008)
)
)
(module
)
5 changes: 5 additions & 0 deletions test/passes/post-emscripten_pass-arg=emscripten-sbrk-ptr@4008.wast
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
(module
(import "env" "emscripten_get_sbrk_ptr" (func $internal(result i32)))
)
(module
)