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CodeGen: Don't follow aliases when extracting type info. 

This fixes a crash in the case where the type info object is an alias
pointing to a non-zero offset within a global or is otherwise unanalyzable
by the stripPointerCasts() function. Looking through the alias is not the
right thing to do anyway for similar reasons as D65118.

Differential Revision: https://reviews.llvm.org/D65314

llvm-svn: 367696
This commit is contained in:
Peter Collingbourne 2019-08-02 17:43:45 +00:00
parent 9ce5f41851
commit 4dcf8800e2
2 changed files with 19 additions and 1 deletions
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2
llvm/lib/CodeGen/Analysis.cpp
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@ -156,7 +156,7 @@ void llvm::computeValueLLTs(const DataLayout &DL, Type &Ty,
/// ExtractTypeInfo - Returns the type info, possibly bitcast, encoded in V.
GlobalValue *llvm::ExtractTypeInfo(Value *V) {
V = V->stripPointerCasts();
V = V->stripPointerCastsNoFollowAliases();
GlobalValue *GV = dyn_cast<GlobalValue>(V);
GlobalVariable *Var = dyn_cast<GlobalVariable>(V);

18
llvm/test/CodeGen/X86/typeid-alias.ll Normal file
View File

@ -0,0 +1,18 @@
; Test that we don't crash in the case where the type info object is an
; alias pointing to a non-zero offset within a global.
; RUN: llc < %s | FileCheck %s
target triple = "x86_64-unknown-linux-gnu"
%struct.exception = type { i8, i8, i32, i8*, i8*, i32, i8* }
@g = global %struct.exception zeroinitializer
@a = alias %struct.exception, %struct.exception* inttoptr (i64 add (i64 ptrtoint (%struct.exception* @g to i64), i64 1297036692682702848) to %struct.exception*)
define i32 @typeid() {
; CHECK: movl $1, %eax
%eh_typeid = tail call i32 @llvm.eh.typeid.for( i8* getelementptr (%struct.exception, %struct.exception* @a, i32 0, i32 0))
ret i32 %eh_typeid
}
declare i32 @llvm.eh.typeid.for(i8*)