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[WebAssembly] Fix unwind mismatch stat computation 

Summary:
There was a bug when computing the number of unwind destination
mismatches in CFGStackify. When there are many mismatched calls that
share the same (original) destination BB, they have to be counted
separately.

This also fixes a typo and runs `fixUnwindMismatches` only when the wasm
exception handling is enabled. This is to prevent unnecessary
computations and does not change behavior.

Reviewers: dschuff

Subscribers: sbc100, jgravelle-google, hiraditya, sunfish, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68552

llvm-svn: 373975
This commit is contained in:
Heejin Ahn 2019-10-07 22:19:40 +00:00
parent ae5bad7277
commit daeead4b02
2 changed files with 9 additions and 3 deletions
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6
llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
View File

@ -848,7 +848,7 @@ bool WebAssemblyCFGStackify::fixUnwindMismatches(MachineFunction &MF) {
SmallVector<const MachineBasicBlock *, 8> EHPadStack;
// Range of intructions to be wrapped in a new nested try/catch
using TryRange = std::pair<MachineInstr *, MachineInstr *>;
// In original CFG, <unwind destionation BB, a vector of try ranges>
// In original CFG, <unwind destination BB, a vector of try ranges>
DenseMap<MachineBasicBlock *, SmallVector<TryRange, 4>> UnwindDestToTryRanges;
// In new CFG, <destination to branch to, a vector of try ranges>
DenseMap<MachineBasicBlock *, SmallVector<TryRange, 4>> BrDestToTryRanges;
@ -985,7 +985,7 @@ bool WebAssemblyCFGStackify::fixUnwindMismatches(MachineFunction &MF) {
// ...
// cont:
for (auto &P : UnwindDestToTryRanges) {
NumUnwindMismatches++;
NumUnwindMismatches += P.second.size();
// This means the destination is the appendix BB, which was separately
// handled above.
@ -1300,6 +1300,8 @@ void WebAssemblyCFGStackify::placeMarkers(MachineFunction &MF) {
}
}
// Fix mismatches in unwind destinations induced by linearizing the code.
if (MCAI->getExceptionHandlingType() == ExceptionHandling::Wasm &&
MF.getFunction().hasPersonalityFn())
fixUnwindMismatches(MF);
}

4
llvm/test/CodeGen/WebAssembly/cfg-stackify-eh.ll
View File

@ -1,6 +1,7 @@
; RUN: llc < %s -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -wasm-keep-registers -disable-block-placement -verify-machineinstrs -fast-isel=false -machine-sink-split-probability-threshold=0 -cgp-freq-ratio-to-skip-merge=1000 -exception-model=wasm -mattr=+exception-handling | FileCheck %s
; RUN: llc < %s -O0 -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -wasm-keep-registers -verify-machineinstrs -exception-model=wasm -mattr=+exception-handling | FileCheck %s --check-prefix=NOOPT
; RUN: llc < %s -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -wasm-keep-registers -disable-block-placement -verify-machineinstrs -fast-isel=false -machine-sink-split-probability-threshold=0 -cgp-freq-ratio-to-skip-merge=1000 -exception-model=wasm -mattr=+exception-handling -wasm-disable-ehpad-sort | FileCheck %s --check-prefix=NOSORT
; RUN: llc < %s -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -wasm-keep-registers -disable-block-placement -verify-machineinstrs -fast-isel=false -machine-sink-split-probability-threshold=0 -cgp-freq-ratio-to-skip-merge=1000 -exception-model=wasm -mattr=+exception-handling -wasm-disable-ehpad-sort -stats 2>&1 | FileCheck %s --check-prefix=NOSORT-STAT
target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
target triple = "wasm32-unknown-unknown"
@ -702,6 +703,9 @@ ehcleanup: ; preds = %entry
cleanupret from %0 unwind to caller
}
; Check if the unwind destination mismatch stats are correct
; NOSORT-STAT: 11 wasm-cfg-stackify - Number of EH pad unwind mismatches found
declare void @foo()
declare void @bar()
declare i32 @baz()