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Differential D69600

[WebAssembly][lld] Fix for static linking of PIC code
ClosedPublic

Authored by sbc100 on Oct 29 2019, 6:38 PM.

Details

Reviewers
jgravelle-google
ruiu
Commits
rGbaff8ec2e1d8: [WebAssembly][lld] Fix for static linking of PIC code
Summary

When statically linking PIC code we create an internalized __memory_base
so that memory-base-relative relocation work correctly. The value of
this global should be zero, and not the globalBase since the globalBase
offset is already taken into account by getVirtualAddress.

Fixes: https://github.com/emscripten-core/emscripten/issues/9013

Diff Detail

Event Timeline

sbc100 created this revision.Oct 29 2019, 6:38 PM
Herald added a project: Restricted Project. · View Herald TranscriptOct 29 2019, 6:38 PM
Herald added subscribers: llvm-commits, sunfish, aheejin and 2 others. · View Herald Transcript
Harbormaster completed remote builds in B40243: Diff 227016.Oct 29 2019, 6:38 PM
sbc100 edited the summary of this revision. (Show Details)Oct 29 2019, 6:39 PM
sbc100 added reviewers: jgravelle-google, ruiu.
ruiu accepted this revision.Oct 29 2019, 6:43 PM

LGTM

This revision is now accepted and ready to land.Oct 29 2019, 6:43 PM
Closed by commit rGbaff8ec2e1d8: [WebAssembly][lld] Fix for static linking of PIC code (authored by sbc100). · Explain WhyOct 29 2019, 7:36 PM
This revision was automatically updated to reflect the committed changes.

Revision Contents

PathSize
lld/
test/
wasm/
2 lines
wasm/
2 lines

Diff 227019

lld/test/wasm/pic-static.ll

Show First 20 Lines • Show All 112 Lines • ▼ Show 20 Lines
; CHECK-NEXT: Value: 1032 ; CHECK-NEXT: Value: 1032
; __memory_base ; __memory_base
; CHECK-NEXT: - Index: 7 ; CHECK-NEXT: - Index: 7
; CHECK-NEXT: Type: I32 ; CHECK-NEXT: Type: I32
; CHECK-NEXT: Mutable: false ; CHECK-NEXT: Mutable: false
; CHECK-NEXT: InitExpr: ; CHECK-NEXT: InitExpr:
; CHECK-NEXT: Opcode: I32_CONST ; CHECK-NEXT: Opcode: I32_CONST
; CHECK-NEXT: Value: 1024 ; CHECK-NEXT: Value: 0

lld/wasm/Writer.cpp

Show First 20 Lines • Show All 220 Lines • ▼ Show 20 Lines if (config->stackFirst) {
placeStack(); placeStack();
} else { } else {
memoryPtr = config->globalBase; memoryPtr = config->globalBase;
log("mem: global base = " + Twine(config->globalBase)); log("mem: global base = " + Twine(config->globalBase));
} }
if (WasmSym::globalBase) if (WasmSym::globalBase)
WasmSym::globalBase->setVirtualAddress(memoryPtr); WasmSym::globalBase->setVirtualAddress(memoryPtr);
if (WasmSym::definedMemoryBase)
WasmSym::definedMemoryBase->setVirtualAddress(memoryPtr);
uint32_t dataStart = memoryPtr; uint32_t dataStart = memoryPtr;
// Arbitrarily set __dso_handle handle to point to the start of the data // Arbitrarily set __dso_handle handle to point to the start of the data
// segments. // segments.
if (WasmSym::dsoHandle) if (WasmSym::dsoHandle)
WasmSym::dsoHandle->setVirtualAddress(dataStart); WasmSym::dsoHandle->setVirtualAddress(dataStart);
▲ Show 20 Lines • Show All 863 Lines • Show Last 20 Lines