WholeProgramDevirt: Create bitcast to i8* at each virtual call site.

We can't reuse the llvm.assume instruction's bitcast because it may not
dominate every user of the vtable pointer.

Differential Revision: https://reviews.llvm.org/D36994

llvm-svn: 311491

llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp

@@ -876,8 +876,9 @@ void DevirtModule::applyUniqueRetValOpt(CallSiteInfo &CSInfo, StringRef FnName,
                                         Constant *UniqueMemberAddr) {
   for (auto &&Call : CSInfo.CallSites) {
     IRBuilder<> B(Call.CS.getInstruction());
-    Value *Cmp = B.CreateICmp(IsOne ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE,
-                              Call.VTable, UniqueMemberAddr);
+    Value *Cmp =
+        B.CreateICmp(IsOne ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE,
+                     B.CreateBitCast(Call.VTable, Int8PtrTy), UniqueMemberAddr);
     Cmp = B.CreateZExt(Cmp, Call.CS->getType());
     Call.replaceAndErase("unique-ret-val", FnName, RemarksEnabled, OREGetter,
                          Cmp);
@@ -943,7 +944,8 @@ void DevirtModule::applyVirtualConstProp(CallSiteInfo &CSInfo, StringRef FnName,
   for (auto Call : CSInfo.CallSites) {
     auto *RetType = cast<IntegerType>(Call.CS.getType());
     IRBuilder<> B(Call.CS.getInstruction());
-    Value *Addr = B.CreateGEP(Int8Ty, Call.VTable, Byte);
+    Value *Addr =
+        B.CreateGEP(Int8Ty, B.CreateBitCast(Call.VTable, Int8PtrTy), Byte);
     if (RetType->getBitWidth() == 1) {
       Value *Bits = B.CreateLoad(Addr);
       Value *BitsAndBit = B.CreateAnd(Bits, Bit);
@@ -1147,8 +1149,7 @@ void DevirtModule::scanTypeTestUsers(Function *TypeTestFunc,
       Value *Ptr = CI->getArgOperand(0)->stripPointerCasts();
       if (SeenPtrs.insert(Ptr).second) {
         for (DevirtCallSite Call : DevirtCalls) {
-          CallSlots[{TypeId, Call.Offset}].addCallSite(CI->getArgOperand(0),
-                                                       Call.CS, nullptr);
+          CallSlots[{TypeId, Call.Offset}].addCallSite(Ptr, Call.CS, nullptr);
         }
       }
     }

llvm/test/Transforms/WholeProgramDevirt/import-no-dominating-assume.ll

@@ -0,0 +1,37 @@
+; RUN: opt -S -wholeprogramdevirt -wholeprogramdevirt-summary-action=import -wholeprogramdevirt-read-summary=%S/Inputs/import-vcp.yaml < %s | FileCheck %s
+
+target datalayout = "e-p:64:64"
+target triple = "x86_64-unknown-linux-gnu"
+
+define i32 @call1(i1 %a, i8* %obj) {
+  %vtableptr = bitcast i8* %obj to [3 x i8*]**
+  %vtable = load [3 x i8*]*, [3 x i8*]** %vtableptr
+  br i1 %a, label %bb1, label %bb2
+
+bb1:
+  ; CHECK: {{.*}} = bitcast {{.*}} to i8*
+  %vtablei8_1 = bitcast [3 x i8*]* %vtable to i8*
+  %p1 = call i1 @llvm.type.test(i8* %vtablei8_1, metadata !"typeid1")
+  call void @llvm.assume(i1 %p1)
+  %fptrptr1 = getelementptr [3 x i8*], [3 x i8*]* %vtable, i32 0, i32 0
+  %fptr1 = load i8*, i8** %fptrptr1
+  %fptr1_casted = bitcast i8* %fptr1 to i32 (i8*, i32)*
+  ; CHECK: {{.*}} = bitcast {{.*}} to i8*
+  %result1 = call i32 %fptr1_casted(i8* %obj, i32 1)
+  br label %bb2
+
+  ; CHECK: :
+bb2:
+  %vtablei8_2 = bitcast [3 x i8*]* %vtable to i8*
+  %p = call i1 @llvm.type.test(i8* %vtablei8_2, metadata !"typeid1")
+  call void @llvm.assume(i1 %p)
+  %fptrptr2 = getelementptr [3 x i8*], [3 x i8*]* %vtable, i32 0, i32 0
+  %fptr2 = load i8*, i8** %fptrptr2
+  %fptr2_casted = bitcast i8* %fptr2 to i32 (i8*, i32)*
+  ; CHECK: {{.*}} = bitcast {{.*}} to i8*
+  %result2 = call i32 %fptr2_casted(i8* %obj, i32 1)
+  ret i32 %result2
+}
+
+declare void @llvm.assume(i1)
+declare i1 @llvm.type.test(i8*, metadata)

llvm/test/Transforms/WholeProgramDevirt/import.ll

@@ -29,6 +29,7 @@ define i32 @call1(i8* %obj) {
   ; SINGLE-IMPL: call i32 bitcast (void ()* @singleimpl1 to i32 (i8*, i32)*)
   %result = call i32 %fptr_casted(i8* %obj, i32 1)
   ; UNIFORM-RET-VAL: ret i32 42
+  ; VCP: {{.*}} = bitcast {{.*}} to i8*
   ; VCP: [[VT1:%.*]] = bitcast {{.*}} to i8*
   ; VCP: [[GEP1:%.*]] = getelementptr i8, i8* [[VT1]], i32 ptrtoint (i8* @__typeid_typeid1_0_1_byte to i32)
   ; VCP: [[BC1:%.*]] = bitcast i8* [[GEP1]] to i32*

llvm/test/Transforms/WholeProgramDevirt/unique-retval.ll

@@ -20,6 +20,7 @@ define i1 @vf1(i8* %this) readnone {
 define i1 @call1(i8* %obj) {
   %vtableptr = bitcast i8* %obj to [1 x i8*]**
   %vtable = load [1 x i8*]*, [1 x i8*]** %vtableptr
+  ; CHECK: {{.*}} = bitcast [1 x i8*]* {{.*}} to i8*
   ; CHECK: [[VT1:%[^ ]*]] = bitcast [1 x i8*]* {{.*}} to i8*
   %vtablei8 = bitcast [1 x i8*]* %vtable to i8*
   %p = call i1 @llvm.type.test(i8* %vtablei8, metadata !"typeid1")

llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-begin.ll

@@ -71,6 +71,7 @@ define i32 @vf4i32(i8* %this) readnone {
 define i1 @call1(i8* %obj) {
   %vtableptr = bitcast i8* %obj to [3 x i8*]**
   %vtable = load [3 x i8*]*, [3 x i8*]** %vtableptr
+  ; CHECK: {{.*}} = bitcast [3 x i8*]* {{.*}} to i8*
   ; CHECK: [[VT1:%[^ ]*]] = bitcast [3 x i8*]* {{.*}} to i8*
   %vtablei8 = bitcast [3 x i8*]* %vtable to i8*
   %p = call i1 @llvm.type.test(i8* %vtablei8, metadata !"typeid")
@@ -91,6 +92,7 @@ define i1 @call1(i8* %obj) {
 define i1 @call2(i8* %obj) {
   %vtableptr = bitcast i8* %obj to [3 x i8*]**
   %vtable = load [3 x i8*]*, [3 x i8*]** %vtableptr
+  ; CHECK: {{.*}} = bitcast [3 x i8*]* {{.*}} to i8*
   ; CHECK: [[VT2:%[^ ]*]] = bitcast [3 x i8*]* {{.*}} to i8*
   %vtablei8 = bitcast [3 x i8*]* %vtable to i8*
   %p = call i1 @llvm.type.test(i8* %vtablei8, metadata !"typeid")
@@ -111,6 +113,7 @@ define i1 @call2(i8* %obj) {
 define i32 @call3(i8* %obj) {
   %vtableptr = bitcast i8* %obj to [3 x i8*]**
   %vtable = load [3 x i8*]*, [3 x i8*]** %vtableptr
+  ; CHECK: {{.*}} = bitcast [3 x i8*]* {{.*}} to i8*
   ; CHECK: [[VT3:%[^ ]*]] = bitcast [3 x i8*]* {{.*}} to i8*
   %vtablei8 = bitcast [3 x i8*]* %vtable to i8*
   %p = call i1 @llvm.type.test(i8* %vtablei8, metadata !"typeid")

llvm/test/Transforms/WholeProgramDevirt/virtual-const-prop-end.ll

@@ -66,6 +66,7 @@ define i32 @vf4i32(i8* %this) readnone {
 define i1 @call1(i8* %obj) {
   %vtableptr = bitcast i8* %obj to [3 x i8*]**
   %vtable = load [3 x i8*]*, [3 x i8*]** %vtableptr
+  ; CHECK: {{.*}} = bitcast [3 x i8*]* {{.*}} to i8*
   ; CHECK: [[VT1:%[^ ]*]] = bitcast [3 x i8*]* {{.*}} to i8*
   %vtablei8 = bitcast [3 x i8*]* %vtable to i8*
   %p = call i1 @llvm.type.test(i8* %vtablei8, metadata !"typeid")
@@ -86,6 +87,7 @@ define i1 @call1(i8* %obj) {
 define i1 @call2(i8* %obj) {
   %vtableptr = bitcast i8* %obj to [3 x i8*]**
   %vtable = load [3 x i8*]*, [3 x i8*]** %vtableptr
+  ; CHECK: {{.*}} = bitcast [3 x i8*]* {{.*}} to i8*
   ; CHECK: [[VT2:%[^ ]*]] = bitcast [3 x i8*]* {{.*}} to i8*
   %vtablei8 = bitcast [3 x i8*]* %vtable to i8*
   %p = call i1 @llvm.type.test(i8* %vtablei8, metadata !"typeid")
@@ -106,6 +108,7 @@ define i1 @call2(i8* %obj) {
 define i32 @call3(i8* %obj) {
   %vtableptr = bitcast i8* %obj to [3 x i8*]**
   %vtable = load [3 x i8*]*, [3 x i8*]** %vtableptr
+  ; CHECK: {{.*}} = bitcast [3 x i8*]* {{.*}} to i8*
   ; CHECK: [[VT3:%[^ ]*]] = bitcast [3 x i8*]* {{.*}} to i8*
   %vtablei8 = bitcast [3 x i8*]* %vtable to i8*
   %p = call i1 @llvm.type.test(i8* %vtablei8, metadata !"typeid")