CallPromotionUtils.cpp File Reference

#include "llvm/Transforms/Utils/CallPromotionUtils.h"
#include "llvm/Analysis/Loads.h"
#include "llvm/Analysis/TypeMetadataUtils.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instructions.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"

Go to the source code of this file.

Macros
#define	DEBUG_TYPE   "call-promotion-utils"

Functions
static void	fixupPHINodeForNormalDest (InvokeInst *Invoke, BasicBlock *OrigBlock, BasicBlock *MergeBlock)
	Fix-up phi nodes in an invoke instruction's normal destination.
static void	fixupPHINodeForUnwindDest (InvokeInst *Invoke, BasicBlock *OrigBlock, BasicBlock *ThenBlock, BasicBlock *ElseBlock)
	Fix-up phi nodes in an invoke instruction's unwind destination.
static void	createRetPHINode (Instruction *OrigInst, Instruction *NewInst, BasicBlock *MergeBlock, IRBuilder<> &Builder)
	Create a phi node for the returned value of a call or invoke instruction.
static void	createRetBitCast (CallBase &CB, Type *RetTy, CastInst **RetBitCast)
	Cast a call or invoke instruction to the given type.

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   "call-promotion-utils"

Definition at line 23 of file CallPromotionUtils.cpp.

Function Documentation

createRetBitCast()

static void createRetBitCast ( CallBase &  CB, Type *  RetTy, CastInst **  RetBitCast  )

static

Cast a call or invoke instruction to the given type.

When promoting a call site, the return type of the call site might not match that of the callee. If this is the case, we have to cast the returned value to the correct type. The location of the cast depends on if we have a call or invoke instruction.

For example, if the call instruction below requires a bitcast after promotion:

orig_bb: t0 = call i32 @func() ...

The bitcast is placed after the call instruction:

orig_bb: ; Uses of the original return value are replaced by uses of the bitcast. t0 = call i32 @func() t1 = bitcast i32 t0 to ... ...

A similar transformation is performed for invoke instructions. However, since invokes are terminating, a new block is created for the bitcast. For example, if the invoke instruction below requires a bitcast after promotion:

orig_bb: t0 = invoke i32 @func() to label normal_dst unwind label unwind_dst

The edge between the original block and the invoke's normal destination is split, and the bitcast is placed there:

orig_bb: t0 = invoke i32 @func() to label split_bb unwind label unwind_dst

split_bb: ; Uses of the original return value are replaced by uses of the bitcast. t1 = bitcast i32 t0 to ... br label normal_dst

Definition at line 162 of file CallPromotionUtils.cpp.

References llvm::CastInst::CreateBitOrPointerCast(), llvm::BasicBlock::front(), llvm::ilist_node_impl< OptionsT >::getIterator(), RetTy, llvm::SplitEdge(), and llvm::Value::users().

Referenced by llvm::promoteCall().

createRetPHINode()

static void createRetPHINode ( Instruction *  OrigInst, Instruction *  NewInst, BasicBlock *  MergeBlock, IRBuilder<> &  Builder  )

static

Create a phi node for the returned value of a call or invoke instruction.

After versioning a call or invoke instruction that returns a value, we have to merge the value of the original and new instructions. We do this by creating a phi node and replacing uses of the original instruction with this phi node.

For example, if OrigInst is defined in "else_bb" and NewInst is defined in "then_bb", we create the following phi node:

; Uses of the original instruction are replaced by uses of the phi node. t0 = phi i32 [ orig_inst, else_bb ], [ new_inst, then_bb ],

Definition at line 107 of file CallPromotionUtils.cpp.

References llvm::PHINode::addIncoming(), Builder, llvm::BasicBlock::front(), llvm::Instruction::getParent(), llvm::Value::getType(), llvm::Type::isVoidTy(), llvm::Value::use_empty(), and llvm::Value::users().

Referenced by llvm::versionCallSite().

fixupPHINodeForNormalDest()

static void fixupPHINodeForNormalDest ( InvokeInst *  Invoke, BasicBlock *  OrigBlock, BasicBlock *  MergeBlock  )

static

Fix-up phi nodes in an invoke instruction's normal destination.

After versioning an invoke instruction, values coming from the original block will now be coming from the "merge" block. For example, in the code below:

then_bb: t0 = invoke i32 ptr() to label merge_bb unwind label unwind_dst

else_bb: t1 = invoke i32 ptr() to label merge_bb unwind label unwind_dst

merge_bb: t2 = phi i32 [ t0, then_bb ], [ t1, else_bb ] br normal_dst

normal_dst: t3 = phi i32 [ x, orig_bb ], ...

"orig_bb" is no longer a predecessor of "normal_dst", so the phi nodes in "normal_dst" must be fixed to refer to "merge_bb":

normal_dst: t3 = phi i32 [ x, merge_bb ], ...

Definition at line 50 of file CallPromotionUtils.cpp.

References llvm::InvokeInst::getNormalDest(), Idx, and llvm::BasicBlock::phis().

Referenced by llvm::versionCallSite().

fixupPHINodeForUnwindDest()

static void fixupPHINodeForUnwindDest ( InvokeInst *  Invoke, BasicBlock *  OrigBlock, BasicBlock *  ThenBlock, BasicBlock *  ElseBlock  )

static

Fix-up phi nodes in an invoke instruction's unwind destination.

After versioning an invoke instruction, values coming from the original block will now be coming from either the "then" block or the "else" block. For example, in the code below:

then_bb: t0 = invoke i32 ptr() to label merge_bb unwind label unwind_dst

else_bb: t1 = invoke i32 ptr() to label merge_bb unwind label unwind_dst

unwind_dst: t3 = phi i32 [ x, orig_bb ], ...

"orig_bb" is no longer a predecessor of "unwind_dst", so the phi nodes in "unwind_dst" must be fixed to refer to "then_bb" and "else_bb":

unwind_dst: t3 = phi i32 [ x, then_bb ], [ x, else_bb ], ...

Definition at line 81 of file CallPromotionUtils.cpp.

References llvm::InvokeInst::getUnwindDest(), Idx, and llvm::BasicBlock::phis().

Referenced by llvm::versionCallSite().