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Fix DeleteDeadVarargs not to crash on functions referenced by BlockAddresses

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This pass was assuming that if hasAddressTaken() returns false for a
function, the function's only uses are call sites.  That's not true
because there can be references by BlockAddresses too.

Fix the pass to handle this case.  Fix
BlockAddress::replaceUsesOfWithOnConstant() to allow a function's type
to be changed by RAUW'ing the function with a bitcast of the recreated
function.

Patch by Mark Seaborn.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183933 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Derek Schuff 2013-06-13 19:51:17 +00:00
parent 6585b388cb
commit c06e5cf2e3
3 changed files with 35 additions and 3 deletions
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2
lib/IR/Constants.cpp
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@ -1389,7 +1389,7 @@ void BlockAddress::replaceUsesOfWithOnConstant(Value *From, Value *To, Use *U) {
BasicBlock *NewBB = getBasicBlock(); BasicBlock *NewBB = getBasicBlock();
if (U == &Op<0>()) if (U == &Op<0>())
NewF = cast<Function>(To); NewF = cast<Function>(To->stripPointerCasts());
else else
NewBB = cast<BasicBlock>(To); NewBB = cast<BasicBlock>(To);

11
lib/Transforms/IPO/DeadArgumentElimination.cpp
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@ -263,8 +263,10 @@ bool DAE::DeleteDeadVarargs(Function &Fn) {
// to pass in a smaller number of arguments into the new function. // to pass in a smaller number of arguments into the new function.
// //
std::vector<Value*> Args; std::vector<Value*> Args;
while (!Fn.use_empty()) { for (Value::use_iterator I = Fn.use_begin(), E = Fn.use_end(); I != E; ) {
CallSite CS(Fn.use_back()); CallSite CS(*I++);
if (!CS)
continue;
Instruction *Call = CS.getInstruction(); Instruction *Call = CS.getInstruction();
// Pass all the same arguments. // Pass all the same arguments.
@ -330,6 +332,11 @@ bool DAE::DeleteDeadVarargs(Function &Fn) {
if (DI != FunctionDIs.end()) if (DI != FunctionDIs.end())
DI->second.replaceFunction(NF); DI->second.replaceFunction(NF);
// Fix up any BlockAddresses that refer to the function.
Fn.replaceAllUsesWith(ConstantExpr::getBitCast(NF, Fn.getType()));
// Delete the bitcast that we just created, so that NF does not
// appear to be address-taken.
NF->removeDeadConstantUsers();
// Finally, nuke the old function. // Finally, nuke the old function.
Fn.eraseFromParent(); Fn.eraseFromParent();
return true; return true;

25
test/Transforms/DeadArgElim/2013-05-17-VarargsAndBlockAddress.ll Normal file
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@ -0,0 +1,25 @@
; RUN: opt %s -deadargelim -S | FileCheck %s
@block_addr = global i8* blockaddress(@varargs_func, %l1)
; CHECK: @block_addr = global i8* blockaddress(@varargs_func, %l1)
; This function is referenced by a "blockaddress" constant but it is
; not address-taken, so the pass should be able to remove its unused
; varargs.
define internal i32 @varargs_func(i8* %addr, ...) {
indirectbr i8* %addr, [ label %l1, label %l2 ]
l1:
ret i32 1
l2:
ret i32 2
}
; CHECK: define internal i32 @varargs_func(i8* %addr) {
define i32 @caller(i8* %addr) {
%r = call i32 (i8*, ...)* @varargs_func(i8* %addr)
ret i32 %r
}
; CHECK: %r = call i32 @varargs_func(i8* %addr)