Assign correct edge weights to unwind destinations when lowering invoke statement.
authorCong Hou <congh@google.com>
Mon, 12 Oct 2015 23:02:58 +0000 (23:02 +0000)
committerCong Hou <congh@google.com>
Mon, 12 Oct 2015 23:02:58 +0000 (23:02 +0000)
When lowering invoke statement, all unwind destinations are directly added as successors of call site block, and the weight of those new edges are not assigned properly. Actually, default weight 16 are used for those edges. This patch calculates the proper edge weights for those edges when collecting all unwind destinations.

Differential revision: http://reviews.llvm.org/D13354

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@250119 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
test/CodeGen/X86/catchpad-weight.ll [new file with mode: 0644]
test/CodeGen/X86/seh-safe-div-win32.ll
test/CodeGen/X86/seh-safe-div.ll
test/CodeGen/X86/win-catchpad.ll

index 70a6f91..3d48346 100644 (file)
@@ -64,6 +64,7 @@
 #include "llvm/Target/TargetSelectionDAGInfo.h"
 #include "llvm/Target/TargetSubtargetInfo.h"
 #include <algorithm>
+#include <utility>
 using namespace llvm;
 
 #define DEBUG_TYPE "isel"
@@ -1243,50 +1244,66 @@ void SelectionDAGBuilder::visitCleanupPad(const CleanupPadInst &CPI) {
 /// destination, but in the machine CFG, we enumerate all the possible blocks.
 /// This function skips over imaginary basic blocks that hold catchpad,
 /// terminatepad, or catchendpad instructions, and finds all the "real" machine
-/// basic block destinations.
-static void
-findUnwindDestinations(FunctionLoweringInfo &FuncInfo,
-                       const BasicBlock *EHPadBB,
-                       SmallVectorImpl<MachineBasicBlock *> &UnwindDests) {
+/// basic block destinations. As those destinations may not be successors of
+/// EHPadBB, here we also calculate the edge weight to those destinations. The
+/// passed-in Weight is the edge weight to EHPadBB.
+static void findUnwindDestinations(
+    FunctionLoweringInfo &FuncInfo, const BasicBlock *EHPadBB, uint32_t Weight,
+    SmallVectorImpl<std::pair<MachineBasicBlock *, uint32_t>> &UnwindDests) {
   EHPersonality Personality =
     classifyEHPersonality(FuncInfo.Fn->getPersonalityFn());
   bool IsMSVCCXX = Personality == EHPersonality::MSVC_CXX;
   bool IsCoreCLR = Personality == EHPersonality::CoreCLR;
+
   while (EHPadBB) {
     const Instruction *Pad = EHPadBB->getFirstNonPHI();
+    BasicBlock *NewEHPadBB = nullptr;
     if (isa<LandingPadInst>(Pad)) {
       // Stop on landingpads. They are not funclets.
-      UnwindDests.push_back(FuncInfo.MBBMap[EHPadBB]);
+      UnwindDests.emplace_back(FuncInfo.MBBMap[EHPadBB], Weight);
       break;
     } else if (isa<CleanupPadInst>(Pad)) {
       // Stop on cleanup pads. Cleanups are always funclet entries for all known
       // personalities.
-      UnwindDests.push_back(FuncInfo.MBBMap[EHPadBB]);
-      UnwindDests.back()->setIsEHFuncletEntry();
+      UnwindDests.emplace_back(FuncInfo.MBBMap[EHPadBB], Weight);
+      UnwindDests.back().first->setIsEHFuncletEntry();
       break;
     } else if (const auto *CPI = dyn_cast<CatchPadInst>(Pad)) {
       // Add the catchpad handler to the possible destinations.
-      UnwindDests.push_back(FuncInfo.MBBMap[EHPadBB]);
+      UnwindDests.emplace_back(FuncInfo.MBBMap[EHPadBB], Weight);
       // In MSVC C++, catchblocks are funclets and need prologues.
       if (IsMSVCCXX || IsCoreCLR)
-        UnwindDests.back()->setIsEHFuncletEntry();
-      EHPadBB = CPI->getUnwindDest();
-    } else if (const auto *CEPI = dyn_cast<CatchEndPadInst>(Pad)) {
-      EHPadBB = CEPI->getUnwindDest();
-    } else if (const auto *CEPI = dyn_cast<CleanupEndPadInst>(Pad)) {
-      EHPadBB = CEPI->getUnwindDest();
+        UnwindDests.back().first->setIsEHFuncletEntry();
+      NewEHPadBB = CPI->getUnwindDest();
+    } else if (const auto *CEPI = dyn_cast<CatchEndPadInst>(Pad))
+      NewEHPadBB = CEPI->getUnwindDest();
+    else if (const auto *CEPI = dyn_cast<CleanupEndPadInst>(Pad))
+      NewEHPadBB = CEPI->getUnwindDest();
+    else
+      continue;
+
+    BranchProbabilityInfo *BPI = FuncInfo.BPI;
+    if (BPI && NewEHPadBB) {
+      // When BPI is available, the calculated weight cannot be zero as zero
+      // will be turned to a default weight in MachineBlockFrequencyInfo.
+      Weight = std::max<uint32_t>(
+          BPI->getEdgeProbability(EHPadBB, NewEHPadBB).scale(Weight), 1);
     }
+    EHPadBB = NewEHPadBB;
   }
 }
 
 void SelectionDAGBuilder::visitCleanupRet(const CleanupReturnInst &I) {
   // Update successor info.
-  // FIXME: The weights for catchpads will be wrong.
-  SmallVector<MachineBasicBlock *, 1> UnwindDests;
-  findUnwindDestinations(FuncInfo, I.getUnwindDest(), UnwindDests);
-  for (MachineBasicBlock *UnwindDest : UnwindDests) {
-    UnwindDest->setIsEHPad();
-    addSuccessorWithWeight(FuncInfo.MBB, UnwindDest);
+  SmallVector<std::pair<MachineBasicBlock *, uint32_t>, 1> UnwindDests;
+  auto UnwindDest = I.getUnwindDest();
+  BranchProbabilityInfo *BPI = FuncInfo.BPI;
+  uint32_t UnwindDestWeight =
+      BPI ? BPI->getEdgeWeight(FuncInfo.MBB->getBasicBlock(), UnwindDest) : 0;
+  findUnwindDestinations(FuncInfo, UnwindDest, UnwindDestWeight, UnwindDests);
+  for (auto &UnwindDest : UnwindDests) {
+    UnwindDest.first->setIsEHPad();
+    addSuccessorWithWeight(FuncInfo.MBB, UnwindDest.first, UnwindDest.second);
   }
 
   // Create the terminator node.
@@ -2128,15 +2145,17 @@ void SelectionDAGBuilder::visitInvoke(const InvokeInst &I) {
     CopyToExportRegsIfNeeded(&I);
   }
 
-  SmallVector<MachineBasicBlock *, 1> UnwindDests;
-  findUnwindDestinations(FuncInfo, EHPadBB, UnwindDests);
+  SmallVector<std::pair<MachineBasicBlock *, uint32_t>, 1> UnwindDests;
+  BranchProbabilityInfo *BPI = FuncInfo.BPI;
+  uint32_t EHPadBBWeight =
+      BPI ? BPI->getEdgeWeight(InvokeMBB->getBasicBlock(), EHPadBB) : 0;
+  findUnwindDestinations(FuncInfo, EHPadBB, EHPadBBWeight, UnwindDests);
 
   // Update successor info.
-  // FIXME: The weights for catchpads will be wrong.
   addSuccessorWithWeight(InvokeMBB, Return);
-  for (MachineBasicBlock *UnwindDest : UnwindDests) {
-    UnwindDest->setIsEHPad();
-    addSuccessorWithWeight(InvokeMBB, UnwindDest);
+  for (auto &UnwindDest : UnwindDests) {
+    UnwindDest.first->setIsEHPad();
+    addSuccessorWithWeight(InvokeMBB, UnwindDest.first, UnwindDest.second);
   }
 
   // Drop into normal successor.
diff --git a/test/CodeGen/X86/catchpad-weight.ll b/test/CodeGen/X86/catchpad-weight.ll
new file mode 100644 (file)
index 0000000..e646d36
--- /dev/null
@@ -0,0 +1,85 @@
+; RUN: llc -march=x86-64 -print-machineinstrs=expand-isel-pseudos %s -o /dev/null 2>&1 | FileCheck %s
+
+; Check if the edge weight to the catchpad is calculated correctly.
+
+; CHECK: Successors according to CFG: BB#3(1048575) BB#1(1) BB#4(1) BB#6(1) BB#8(1)
+
+target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64--windows-msvc18.0.0"
+
+%rtti.TypeDescriptor7 = type { i8**, i8*, [8 x i8] }
+%struct.HasDtor = type { i8 }
+
+$"\01??_R0?AUA@@@8" = comdat any
+
+$"\01??_R0?AUB@@@8" = comdat any
+
+$"\01??_R0?AUC@@@8" = comdat any
+
+@"\01??_7type_info@@6B@" = external constant i8*
+@"\01??_R0?AUA@@@8" = linkonce_odr global %rtti.TypeDescriptor7 { i8** @"\01??_7type_info@@6B@", i8* null, [8 x i8] c".?AUA@@\00" }, comdat
+@"\01??_R0?AUB@@@8" = linkonce_odr global %rtti.TypeDescriptor7 { i8** @"\01??_7type_info@@6B@", i8* null, [8 x i8] c".?AUB@@\00" }, comdat
+@"\01??_R0?AUC@@@8" = linkonce_odr global %rtti.TypeDescriptor7 { i8** @"\01??_7type_info@@6B@", i8* null, [8 x i8] c".?AUC@@\00" }, comdat
+
+; Function Attrs: uwtable
+define i32 @main() #0 personality i8* bitcast (i32 (...)* @__CxxFrameHandler3 to i8*) {
+entry:
+  %o = alloca %struct.HasDtor, align 1
+  %0 = getelementptr inbounds %struct.HasDtor, %struct.HasDtor* %o, i64 0, i32 0
+  call void @llvm.lifetime.start(i64 1, i8* %0) #4
+  invoke void @"\01?may_throw@@YAXXZ"()
+          to label %try.cont unwind label %catch.dispatch
+
+catch.dispatch:                                   ; preds = %entry
+  %1 = catchpad [%rtti.TypeDescriptor7* @"\01??_R0?AUA@@@8", i32 0, i8* null]
+          to label %catch.5 unwind label %catch.dispatch.1
+
+catch.5:                                          ; preds = %catch.dispatch
+  catchret %1 to label %try.cont
+
+try.cont:                                         ; preds = %entry, %catch, %catch.3, %catch.5
+  call void @"\01??1HasDtor@@QEAA@XZ"(%struct.HasDtor* nonnull %o) #4
+  call void @llvm.lifetime.end(i64 1, i8* %0) #4
+  ret i32 0
+
+catch.dispatch.1:                                 ; preds = %catch.dispatch
+  %2 = catchpad [%rtti.TypeDescriptor7* @"\01??_R0?AUB@@@8", i32 0, i8* null]
+          to label %catch.3 unwind label %catch.dispatch.2
+
+catch.3:                                          ; preds = %catch.dispatch.1
+  catchret %2 to label %try.cont
+
+catch.dispatch.2:                                 ; preds = %catch.dispatch.1
+  %3 = catchpad [%rtti.TypeDescriptor7* @"\01??_R0?AUC@@@8", i32 0, i8* null]
+          to label %catch unwind label %catchendblock
+
+catch:                                            ; preds = %catch.dispatch.2
+  catchret %3 to label %try.cont
+
+catchendblock:                                    ; preds = %catch.dispatch.2
+  catchendpad unwind label %ehcleanup
+
+ehcleanup:                                        ; preds = %catchendblock
+  %4 = cleanuppad []
+  call void @"\01??1HasDtor@@QEAA@XZ"(%struct.HasDtor* nonnull %o) #4
+  cleanupret %4 unwind to caller
+}
+
+; Function Attrs: nounwind argmemonly
+declare void @llvm.lifetime.start(i64, i8* nocapture) #1
+
+declare void @"\01?may_throw@@YAXXZ"() #2
+
+declare i32 @__CxxFrameHandler3(...)
+
+; Function Attrs: nounwind
+declare void @"\01??1HasDtor@@QEAA@XZ"(%struct.HasDtor*) #3
+
+; Function Attrs: nounwind argmemonly
+declare void @llvm.lifetime.end(i64, i8* nocapture) #1
+
+attributes #0 = { uwtable "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+mmx,+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nounwind argmemonly }
+attributes #2 = { "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+mmx,+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #3 = { nounwind "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+mmx,+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #4 = { nounwind }
index d17f221..7f83b0c 100644 (file)
@@ -71,13 +71,13 @@ __try.cont:
 
 ; Landing pad code
 
-; CHECK: [[lpad1:LBB0_[0-9]+]]: # %lpad1
+; CHECK: [[lpad0:LBB0_[0-9]+]]: # %lpad0
 ;      Restore SP
 ; CHECK: movl {{.*}}(%ebp), %esp
 ; CHECK: calll _puts
 ; CHECK: jmp [[cont_bb]]
 
-; CHECK: [[lpad0:LBB0_[0-9]+]]: # %lpad0
+; CHECK: [[lpad1:LBB0_[0-9]+]]: # %lpad1
 ;      Restore SP
 ; CHECK: movl {{.*}}(%ebp), %esp
 ; CHECK: calll _puts
index 809d261..1c7318b 100644 (file)
@@ -73,14 +73,14 @@ __try.cont:
 
 ; Landing pad code
 
-; CHECK: [[lpad1:\.LBB0_[0-9]+]]: # %lpad1
+; CHECK: [[lpad0:\.LBB0_[0-9]+]]: # %lpad0
 ; CHECK: callq puts
-; CHECK: movl $-2, [[rloc]]
+; CHECK: movl $-1, [[rloc]]
 ; CHECK: jmp [[cont_bb]]
 
-; CHECK: [[lpad0:\.LBB0_[0-9]+]]: # %lpad0
+; CHECK: [[lpad1:\.LBB0_[0-9]+]]: # %lpad1
 ; CHECK: callq puts
-; CHECK: movl $-1, [[rloc]]
+; CHECK: movl $-2, [[rloc]]
 ; CHECK: jmp [[cont_bb]]
 
 ; CHECK: .seh_handlerdata
index 78a8fcf..7761839 100644 (file)
@@ -74,13 +74,13 @@ catchendblock:                                    ; preds = %catch, %catch.2, %c
 ; X86: [[contbb:LBB0_[0-9]+]]: # %try.cont
 ; X86: retl
 
-; FIXME: These should be de-duplicated.
-; X86: [[restorebb2:LBB0_[0-9]+]]: # %invoke.cont.3
+; X86: [[restorebb1:LBB0_[0-9]+]]: # %invoke.cont.2
 ; X86: movl -16(%ebp), %esp
 ; X86: addl $12, %ebp
 ; X86: jmp [[contbb]]
 
-; X86: [[restorebb1:LBB0_[0-9]+]]: # %invoke.cont.2
+; FIXME: These should be de-duplicated.
+; X86: [[restorebb2:LBB0_[0-9]+]]: # %invoke.cont.3
 ; X86: movl -16(%ebp), %esp
 ; X86: addl $12, %ebp
 ; X86: jmp [[contbb]]