[PATCH] D77124: Handle CET for -exception-model sjlj

[Xiang Zhang via Phabricator via llvm-commits]

xiangzhangllvm created this revision.
xiangzhangllvm added reviewers: hjl.tools, craig.topper, annita.zhang, LuoYuanke, pengfei, efriedma.
Herald added subscribers: llvm-commits, hiraditya.
Herald added a project: LLVM.

In SjLj exception mode, the old landingpad BB may create a new landingpad BB and use indirect branch jump to the old landingpad BB in lowering.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D77124

Files:
  llvm/lib/Target/X86/X86IndirectBranchTracking.cpp
  llvm/test/CodeGen/X86/indirect-branch-tracking-eh.ll


Index: llvm/test/CodeGen/X86/indirect-branch-tracking-eh.ll
===================================================================
--- llvm/test/CodeGen/X86/indirect-branch-tracking-eh.ll
+++ llvm/test/CodeGen/X86/indirect-branch-tracking-eh.ll
@@ -1,15 +1,25 @@
-; RUN: llc -mtriple=x86_64-unknown-unknown < %s | FileCheck %s
-; RUN: llc -mtriple=i386-unknown-unknown < %s | FileCheck %s
+; RUN: llc -mtriple=x86_64-unknown-unknown < %s | FileCheck %s --check-prefix=X86_64
+; RUN: llc -mtriple=i386-unknown-unknown < %s | FileCheck %s --check-prefix=X86
+; RUN: llc -mtriple i386-windows-gnu -exception-model sjlj -verify-machineinstrs=0 < %s | FileCheck %s --check-prefix=SJLJ
 
-;There should be 2 endbr* instruction at entry and catch pad.
-;CHECK-COUNT-2: endbr
+; ALL-LABEL:   test_eh
+; X86_64:      endbr64
+; X86:         endbr32
+; SJLJ:        endbr32
+; ALL:         call{{.}}   __Z20function_that_throwsv
+; SJLJ:        LBB0_{{.}}:
+; SJLJ:        endbr32
+; ALL:         LBB0_{{.}}:   # %lpad
+; X86_64:      endbr64
+; X86:         endbr32
+; SJLJ:        endbr32
 
 declare void @_Z20function_that_throwsv()
 declare i32 @__gxx_personality_sj0(...)
 declare i8* @__cxa_begin_catch(i8*)
 declare void @__cxa_end_catch()
 
-define void @test8() personality i8* bitcast (i32 (...)* @__gxx_personality_sj0 to i8*) {
+define void @test_eh() personality i8* bitcast (i32 (...)* @__gxx_personality_sj0 to i8*) {
 entry:
   invoke void @_Z20function_that_throwsv()
           to label %try.cont unwind label %lpad
Index: llvm/lib/Target/X86/X86IndirectBranchTracking.cpp
===================================================================
--- llvm/lib/Target/X86/X86IndirectBranchTracking.cpp
+++ llvm/lib/Target/X86/X86IndirectBranchTracking.cpp
@@ -127,15 +127,27 @@
     if (MBB.hasAddressTaken())
       Changed |= addENDBR(MBB, MBB.begin());
 
-    // Exception handle may indirectly jump to catch pad, So we should add
-    // ENDBR before catch pad instructions.
-    bool EHPadIBTNeeded = MBB.isEHPad();
+    bool EHPadIBTNeeded = true;
+    bool isEHPadBB = MBB.isEHPad();
 
     for (MachineBasicBlock::iterator I = MBB.begin(); I != MBB.end(); ++I) {
       if (I->isCall() && IsCallReturnTwice(I->getOperand(0)))
         Changed |= addENDBR(MBB, std::next(I));
 
-      if (EHPadIBTNeeded && I->isEHLabel()) {
+      // Exception handle may indirectly jump to catch pad, So we should add
+      // ENDBR before catch pad instructions. For some exception mode, the old
+      // landingpad BB may create a new landingpad BB and use indirect branch
+      // jump to the old landingpad BB in lowering.
+      if (isEHPadBB && !I->isDebugInstr() && EHPadIBTNeeded) {
+        if (I->isEHLabel())
+          Changed |= addENDBR(MBB, std::next(I));
+        else
+          Changed |= addENDBR(MBB, I);
+        EHPadIBTNeeded = false;
+      }
+      if (!isEHPadBB && I->isEHLabel() && EHPadIBTNeeded) {
+        MCSymbol *Sym = I->getOperand(0).getMCSymbol();
+        if (MF.hasCallSiteLandingPad(Sym))
           Changed |= addENDBR(MBB, std::next(I));
           EHPadIBTNeeded = false;
       }


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D77124.253812.patch
Type: text/x-patch
Size: 3117 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20200331/54e463cd/attachment-0001.bin>