RPCS3/llvm-mirror
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm-mirror.git synced 2025-01-31 12:41:49 +01:00
Code Issues Projects Releases Wiki Activity

[ConstantHoisting] Avoid hoisting constants in GEPs that index into a struct type.

Browse Source 
Summary:
Indices for GEPs that index into a struct type should always be
constants. This added more checks in `collectConstantCandidates:` which make
sure constants for GEP pointer type are not hoisted.

This fixed Bug https://bugs.llvm.org/show_bug.cgi?id=33538

Reviewers: ributzka, rnk

Reviewed By: ributzka

Subscribers: efriedma, llvm-commits, srhines, javed.absar, pirama

Differential Revision: https://reviews.llvm.org/D34576

llvm-svn: 306704
This commit is contained in:
Leo Li 2017-06-29 17:03:34 +00:00
parent 304d4ef792
commit 9f55e00ae0
3 changed files with 100 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/llvm/Transforms/Scalar/ConstantHoisting.h
View File

@ -131,6 +131,8 @@ private:
void collectConstantCandidates(ConstCandMapType &ConstCandMap,
Instruction *Inst, unsigned Idx,
ConstantInt *ConstInt);
void collectConstantCandidates(ConstCandMapType &ConstCandMap,
Instruction *Inst, unsigned Idx);
void collectConstantCandidates(ConstCandMapType &ConstCandMap,
Instruction *Inst);
void collectConstantCandidates(Function &Fn);

97
lib/Transforms/Scalar/ConstantHoisting.cpp
View File

@ -38,6 +38,7 @@
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/GetElementPtrTypeIterator.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
@ -340,6 +341,49 @@ void ConstantHoistingPass::collectConstantCandidates(
}
}
/// \brief Check the operand for instruction Inst at index Idx.
void ConstantHoistingPass::collectConstantCandidates(
ConstCandMapType &ConstCandMap, Instruction *Inst, unsigned Idx) {
Value *Opnd = Inst->getOperand(Idx);
// Visit constant integers.
if (auto ConstInt = dyn_cast<ConstantInt>(Opnd)) {
collectConstantCandidates(ConstCandMap, Inst, Idx, ConstInt);
return;
}
// Visit cast instructions that have constant integers.
if (auto CastInst = dyn_cast<Instruction>(Opnd)) {
// Only visit cast instructions, which have been skipped. All other
// instructions should have already been visited.
if (!CastInst->isCast())
return;
if (auto *ConstInt = dyn_cast<ConstantInt>(CastInst->getOperand(0))) {
// Pretend the constant is directly used by the instruction and ignore
// the cast instruction.
collectConstantCandidates(ConstCandMap, Inst, Idx, ConstInt);
return;
}
}
// Visit constant expressions that have constant integers.
if (auto ConstExpr = dyn_cast<ConstantExpr>(Opnd)) {
// Only visit constant cast expressions.
if (!ConstExpr->isCast())
return;
if (auto ConstInt = dyn_cast<ConstantInt>(ConstExpr->getOperand(0))) {
// Pretend the constant is directly used by the instruction and ignore
// the constant expression.
collectConstantCandidates(ConstCandMap, Inst, Idx, ConstInt);
return;
}
}
}
/// \brief Scan the instruction for expensive integer constants and record them
/// in the constant candidate vector.
void ConstantHoistingPass::collectConstantCandidates(
@ -365,44 +409,25 @@ void ConstantHoistingPass::collectConstantCandidates(
if (AI && AI->isStaticAlloca())
return;
// Constants in GEPs that index into a struct type should not be hoisted.
if (isa<GetElementPtrInst>(Inst)) {
gep_type_iterator GTI = gep_type_begin(Inst);
// Collect constant for first operand.
collectConstantCandidates(ConstCandMap, Inst, 0);
// Scan rest operands.
for (unsigned Idx = 1, E = Inst->getNumOperands(); Idx != E; ++Idx, ++GTI) {
// Only collect constants that index into a non struct type.
if (!GTI.isStruct()) {
collectConstantCandidates(ConstCandMap, Inst, Idx);
}
}
return;
}
// Scan all operands.
for (unsigned Idx = 0, E = Inst->getNumOperands(); Idx != E; ++Idx) {
Value *Opnd = Inst->getOperand(Idx);
// Visit constant integers.
if (auto ConstInt = dyn_cast<ConstantInt>(Opnd)) {
collectConstantCandidates(ConstCandMap, Inst, Idx, ConstInt);
continue;
}
// Visit cast instructions that have constant integers.
if (auto CastInst = dyn_cast<Instruction>(Opnd)) {
// Only visit cast instructions, which have been skipped. All other
// instructions should have already been visited.
if (!CastInst->isCast())
continue;
if (auto *ConstInt = dyn_cast<ConstantInt>(CastInst->getOperand(0))) {
// Pretend the constant is directly used by the instruction and ignore
// the cast instruction.
collectConstantCandidates(ConstCandMap, Inst, Idx, ConstInt);
continue;
}
}
// Visit constant expressions that have constant integers.
if (auto ConstExpr = dyn_cast<ConstantExpr>(Opnd)) {
// Only visit constant cast expressions.
if (!ConstExpr->isCast())
continue;
if (auto ConstInt = dyn_cast<ConstantInt>(ConstExpr->getOperand(0))) {
// Pretend the constant is directly used by the instruction and ignore
// the constant expression.
collectConstantCandidates(ConstCandMap, Inst, Idx, ConstInt);
continue;
}
}
collectConstantCandidates(ConstCandMap, Inst, Idx);
} // end of for all operands
}

37
test/Transforms/ConstantHoisting/ARM/gep-struct-index.ll Normal file
View File

@ -0,0 +1,37 @@
; RUN: opt -consthoist -S < %s | FileCheck %s
target triple = "thumbv6m-none-eabi"
%T = type { i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32,
i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32,
i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32,
i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32,
i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32,
i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32,
i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32,
i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32,
i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32,
i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32,
i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32,
i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32,
i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32,
i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32,
i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32,
i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32,
i32, i32, i32, i32, i32, i32 }
; Indices for GEPs that index into a struct type should not be hoisted.
define i32 @test1(%T* %P) nounwind {
; CHECK-LABEL: @test1
; CHECK: %const = bitcast i32 256 to i32
; CHECK: %addr1 = getelementptr %T, %T* %P, i32 %const, i32 256
; CHECK: %addr2 = getelementptr %T, %T* %P, i32 %const, i32 256
; The first index into the pointer is hoisted, but the second one into the
; struct isn't.
%addr1 = getelementptr %T, %T* %P, i32 256, i32 256
%tmp1 = load i32, i32* %addr1
%addr2 = getelementptr %T, %T* %P, i32 256, i32 256
%tmp2 = load i32, i32* %addr2
%tmp4 = add i32 %tmp1, %tmp2
ret i32 %tmp4
}