[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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@373975 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp b/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
index 6b2094679cea54f5a88237b9ae5493d361670809..d2a35574e2feedf4a12adcb19176504b424fa332 100644 (file)
--- a/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
+++ b/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
@@ -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.
@@ -1300,7 +1300,9 @@ void WebAssemblyCFGStackify::placeMarkers(MachineFunction &MF) {
     }
   }
   // Fix mismatches in unwind destinations induced by linearizing the code.
-  fixUnwindMismatches(MF);
+  if (MCAI->getExceptionHandlingType() == ExceptionHandling::Wasm &&
+      MF.getFunction().hasPersonalityFn())
+    fixUnwindMismatches(MF);
 }
 
 void WebAssemblyCFGStackify::rewriteDepthImmediates(MachineFunction &MF) {

diff --git a/test/CodeGen/WebAssembly/cfg-stackify-eh.ll b/test/CodeGen/WebAssembly/cfg-stackify-eh.ll
index c79eb935179f04d006f6006e8798451e291b1573..f33f56701ebb81cead57c31c4cf954544d7d6a26 100644 (file)
--- a/test/CodeGen/WebAssembly/cfg-stackify-eh.ll
+++ b/test/CodeGen/WebAssembly/cfg-stackify-eh.ll
@@ -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()