Remove alignment argument from memcpy/memmove/memset in favour of alignment attributes (Step 1)
Summary:
This is a resurrection of work first proposed and discussed in Aug 2015:
http://lists.llvm.org/pipermail/llvm-dev/2015-August/089384.html
and initially landed (but then backed out) in Nov 2015:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20151109/312083.html
The @llvm.memcpy/memmove/memset intrinsics currently have an explicit argument
which is required to be a constant integer. It represents the alignment of the
dest (and source), and so must be the minimum of the actual alignment of the
two.
This change is the first in a series that allows source and dest to each
have their own alignments by using the alignment attribute on their arguments.
In this change we:
1) Remove the alignment argument.
2) Add alignment attributes to the source & dest arguments. We, temporarily,
require that the alignments for source & dest be equal.
For example, code which used to read:
call void @llvm.memcpy.p0i8.p0i8.i32(i8* %dest, i8* %src, i32 100, i32 4, i1 false)
will now read
call void @llvm.memcpy.p0i8.p0i8.i32(i8* align 4 %dest, i8* align 4 %src, i32 100, i1 false)
Downstream users may have to update their lit tests that check for
@llvm.memcpy/memmove/memset call/declaration patterns. The following extended sed script
may help with updating the majority of your tests, but it does not catch all possible
patterns so some manual checking and updating will be required.
s~declare void @llvm\.mem(set|cpy|move)\.p([^(]*)\((.*), i32, i1\)~declare void @llvm.mem\1.p\2(\3, i1)~g
s~call void @llvm\.memset\.p([^(]*)i8\(i8([^*]*)\* (.*), i8 (.*), i8 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.memset.p\1i8(i8\2* \3, i8 \4, i8 \5, i1 \6)~g
s~call void @llvm\.memset\.p([^(]*)i16\(i8([^*]*)\* (.*), i8 (.*), i16 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.memset.p\1i16(i8\2* \3, i8 \4, i16 \5, i1 \6)~g
s~call void @llvm\.memset\.p([^(]*)i32\(i8([^*]*)\* (.*), i8 (.*), i32 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.memset.p\1i32(i8\2* \3, i8 \4, i32 \5, i1 \6)~g
s~call void @llvm\.memset\.p([^(]*)i64\(i8([^*]*)\* (.*), i8 (.*), i64 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.memset.p\1i64(i8\2* \3, i8 \4, i64 \5, i1 \6)~g
s~call void @llvm\.memset\.p([^(]*)i128\(i8([^*]*)\* (.*), i8 (.*), i128 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.memset.p\1i128(i8\2* \3, i8 \4, i128 \5, i1 \6)~g
s~call void @llvm\.memset\.p([^(]*)i8\(i8([^*]*)\* (.*), i8 (.*), i8 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.memset.p\1i8(i8\2* align \6 \3, i8 \4, i8 \5, i1 \7)~g
s~call void @llvm\.memset\.p([^(]*)i16\(i8([^*]*)\* (.*), i8 (.*), i16 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.memset.p\1i16(i8\2* align \6 \3, i8 \4, i16 \5, i1 \7)~g
s~call void @llvm\.memset\.p([^(]*)i32\(i8([^*]*)\* (.*), i8 (.*), i32 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.memset.p\1i32(i8\2* align \6 \3, i8 \4, i32 \5, i1 \7)~g
s~call void @llvm\.memset\.p([^(]*)i64\(i8([^*]*)\* (.*), i8 (.*), i64 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.memset.p\1i64(i8\2* align \6 \3, i8 \4, i64 \5, i1 \7)~g
s~call void @llvm\.memset\.p([^(]*)i128\(i8([^*]*)\* (.*), i8 (.*), i128 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.memset.p\1i128(i8\2* align \6 \3, i8 \4, i128 \5, i1 \7)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i8\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i8 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.mem\1.p\2i8(i8\3* \4, i8\5* \6, i8 \7, i1 \8)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i16\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i16 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.mem\1.p\2i16(i8\3* \4, i8\5* \6, i16 \7, i1 \8)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i32\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i32 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.mem\1.p\2i32(i8\3* \4, i8\5* \6, i32 \7, i1 \8)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i64\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i64 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.mem\1.p\2i64(i8\3* \4, i8\5* \6, i64 \7, i1 \8)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i128\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i128 (.*), i32 [01], i1 ([^)]*)\)~call void @llvm.mem\1.p\2i128(i8\3* \4, i8\5* \6, i128 \7, i1 \8)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i8\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i8 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.mem\1.p\2i8(i8\3* align \8 \4, i8\5* align \8 \6, i8 \7, i1 \9)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i16\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i16 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.mem\1.p\2i16(i8\3* align \8 \4, i8\5* align \8 \6, i16 \7, i1 \9)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i32\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i32 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.mem\1.p\2i32(i8\3* align \8 \4, i8\5* align \8 \6, i32 \7, i1 \9)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i64\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i64 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.mem\1.p\2i64(i8\3* align \8 \4, i8\5* align \8 \6, i64 \7, i1 \9)~g
s~call void @llvm\.mem(cpy|move)\.p([^(]*)i128\(i8([^*]*)\* (.*), i8([^*]*)\* (.*), i128 (.*), i32 ([0-9]*), i1 ([^)]*)\)~call void @llvm.mem\1.p\2i128(i8\3* align \8 \4, i8\5* align \8 \6, i128 \7, i1 \9)~g
The remaining changes in the series will:
Step 2) Expand the IRBuilder API to allow creation of memcpy/memmove with differing
source and dest alignments.
Step 3) Update Clang to use the new IRBuilder API.
Step 4) Update Polly to use the new IRBuilder API.
Step 5) Update LLVM passes that create memcpy/memmove calls to use the new IRBuilder API,
and those that use use MemIntrinsicInst::[get|set]Alignment() to use
getDestAlignment() and getSourceAlignment() instead.
Step 6) Remove the single-alignment IRBuilder API for memcpy/memmove, and the
MemIntrinsicInst::[get|set]Alignment() methods.
Reviewers: pete, hfinkel, lhames, reames, bollu
Reviewed By: reames
Subscribers: niosHD, reames, jholewinski, qcolombet, jfb, sanjoy, arsenm, dschuff, dylanmckay, mehdi_amini, sdardis, nemanjai, david2050, nhaehnle, javed.absar, sbc100, jgravelle-google, eraman, aheejin, kbarton, JDevlieghere, asb, rbar, johnrusso, simoncook, jordy.potman.lists, apazos, sabuasal, llvm-commits
Differential Revision: https://reviews.llvm.org/D41675
llvm-svn: 322965
diff --git a/llvm/lib/IR/AutoUpgrade.cpp b/llvm/lib/IR/AutoUpgrade.cpp
index bf96e77..5d21999 100644
--- a/llvm/lib/IR/AutoUpgrade.cpp
+++ b/llvm/lib/IR/AutoUpgrade.cpp
@@ -22,6 +22,7 @@
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instruction.h"
+#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Verifier.h"
@@ -522,6 +523,37 @@
return true;
}
}
+ // Updating the memory intrinsics (memcpy/memmove/memset) that have an
+ // alignment parameter to embedding the alignment as an attribute of
+ // the pointer args.
+ if (Name.startswith("memcpy.") && F->arg_size() == 5) {
+ rename(F);
+ // Get the types of dest, src, and len
+ ArrayRef<Type *> ParamTypes = F->getFunctionType()->params().slice(0, 3);
+ NewFn = Intrinsic::getDeclaration(F->getParent(), Intrinsic::memcpy,
+ ParamTypes);
+ return true;
+ }
+ if (Name.startswith("memmove.") && F->arg_size() == 5) {
+ rename(F);
+ // Get the types of dest, src, and len
+ ArrayRef<Type *> ParamTypes = F->getFunctionType()->params().slice(0, 3);
+ NewFn = Intrinsic::getDeclaration(F->getParent(), Intrinsic::memmove,
+ ParamTypes);
+ return true;
+ }
+ if (Name.startswith("memset.") && F->arg_size() == 5) {
+ rename(F);
+ // Get the types of dest, and len
+ const auto *FT = F->getFunctionType();
+ Type *ParamTypes[2] = {
+ FT->getParamType(0), // Dest
+ FT->getParamType(2) // len
+ };
+ NewFn = Intrinsic::getDeclaration(F->getParent(), Intrinsic::memset,
+ ParamTypes);
+ return true;
+ }
break;
}
case 'n': {
@@ -2198,14 +2230,17 @@
return;
}
- CallInst *NewCall = nullptr;
- switch (NewFn->getIntrinsicID()) {
- default: {
+ const auto &DefaultCase = [&NewFn, &CI]() -> void {
// Handle generic mangling change, but nothing else
assert(
(CI->getCalledFunction()->getName() != NewFn->getName()) &&
"Unknown function for CallInst upgrade and isn't just a name change");
CI->setCalledFunction(NewFn);
+ };
+ CallInst *NewCall = nullptr;
+ switch (NewFn->getIntrinsicID()) {
+ default: {
+ DefaultCase();
return;
}
@@ -2346,6 +2381,35 @@
NewCall = Builder.CreateCall(NewFn, Args);
break;
}
+
+ case Intrinsic::memcpy:
+ case Intrinsic::memmove:
+ case Intrinsic::memset: {
+ // We have to make sure that the call signature is what we're expecting.
+ // We only want to change the old signatures by removing the alignment arg:
+ // @llvm.mem[cpy|move]...(i8*, i8*, i[32|i64], i32, i1)
+ // -> @llvm.mem[cpy|move]...(i8*, i8*, i[32|i64], i1)
+ // @llvm.memset...(i8*, i8, i[32|64], i32, i1)
+ // -> @llvm.memset...(i8*, i8, i[32|64], i1)
+ // Note: i8*'s in the above can be any pointer type
+ if (CI->getNumArgOperands() != 5) {
+ DefaultCase();
+ return;
+ }
+ // Remove alignment argument (3), and add alignment attributes to the
+ // dest/src pointers.
+ Value *Args[4] = {CI->getArgOperand(0), CI->getArgOperand(1),
+ CI->getArgOperand(2), CI->getArgOperand(4)};
+ NewCall = Builder.CreateCall(NewFn, Args);
+ auto *MemCI = cast<MemIntrinsic>(NewCall);
+ // All mem intrinsics support dest alignment.
+ const ConstantInt *Align = cast<ConstantInt>(CI->getArgOperand(3));
+ MemCI->setDestAlignment(Align->getZExtValue());
+ // Memcpy/Memmove also support source alignment.
+ if (auto *MTI = dyn_cast<MemTransferInst>(MemCI))
+ MTI->setSourceAlignment(Align->getZExtValue());
+ break;
+ }
}
assert(NewCall && "Should have either set this variable or returned through "
"the default case");
diff --git a/llvm/lib/IR/IRBuilder.cpp b/llvm/lib/IR/IRBuilder.cpp
index 027c025..99795f5 100644
--- a/llvm/lib/IR/IRBuilder.cpp
+++ b/llvm/lib/IR/IRBuilder.cpp
@@ -15,6 +15,7 @@
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalVariable.h"
+#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Statepoint.h"
@@ -83,13 +84,16 @@
bool isVolatile, MDNode *TBAATag, MDNode *ScopeTag,
MDNode *NoAliasTag) {
Ptr = getCastedInt8PtrValue(Ptr);
- Value *Ops[] = { Ptr, Val, Size, getInt32(Align), getInt1(isVolatile) };
+ Value *Ops[] = {Ptr, Val, Size, getInt1(isVolatile)};
Type *Tys[] = { Ptr->getType(), Size->getType() };
Module *M = BB->getParent()->getParent();
Value *TheFn = Intrinsic::getDeclaration(M, Intrinsic::memset, Tys);
CallInst *CI = createCallHelper(TheFn, Ops, this);
-
+
+ if (Align > 0)
+ cast<MemSetInst>(CI)->setDestAlignment(Align);
+
// Set the TBAA info if present.
if (TBAATag)
CI->setMetadata(LLVMContext::MD_tbaa, TBAATag);
@@ -99,7 +103,7 @@
if (NoAliasTag)
CI->setMetadata(LLVMContext::MD_noalias, NoAliasTag);
-
+
return CI;
}
@@ -107,16 +111,20 @@
CreateMemCpy(Value *Dst, Value *Src, Value *Size, unsigned Align,
bool isVolatile, MDNode *TBAATag, MDNode *TBAAStructTag,
MDNode *ScopeTag, MDNode *NoAliasTag) {
+ assert((Align == 0 || isPowerOf2_32(Align)) && "Must be 0 or a power of 2");
Dst = getCastedInt8PtrValue(Dst);
Src = getCastedInt8PtrValue(Src);
- Value *Ops[] = { Dst, Src, Size, getInt32(Align), getInt1(isVolatile) };
+ Value *Ops[] = {Dst, Src, Size, getInt1(isVolatile)};
Type *Tys[] = { Dst->getType(), Src->getType(), Size->getType() };
Module *M = BB->getParent()->getParent();
Value *TheFn = Intrinsic::getDeclaration(M, Intrinsic::memcpy, Tys);
CallInst *CI = createCallHelper(TheFn, Ops, this);
-
+
+ if (Align > 0)
+ cast<MemCpyInst>(CI)->setAlignment(Align);
+
// Set the TBAA info if present.
if (TBAATag)
CI->setMetadata(LLVMContext::MD_tbaa, TBAATag);
@@ -130,7 +138,7 @@
if (NoAliasTag)
CI->setMetadata(LLVMContext::MD_noalias, NoAliasTag);
-
+
return CI;
}
@@ -154,8 +162,9 @@
CallInst *CI = createCallHelper(TheFn, Ops, this);
// Set the alignment of the pointer args.
- CI->addParamAttr(0, Attribute::getWithAlignment(CI->getContext(), DstAlign));
- CI->addParamAttr(1, Attribute::getWithAlignment(CI->getContext(), SrcAlign));
+ auto *AMCI = cast<AtomicMemCpyInst>(CI);
+ AMCI->setDestAlignment(DstAlign);
+ AMCI->setSourceAlignment(SrcAlign);
// Set the TBAA info if present.
if (TBAATag)
@@ -178,16 +187,21 @@
CreateMemMove(Value *Dst, Value *Src, Value *Size, unsigned Align,
bool isVolatile, MDNode *TBAATag, MDNode *ScopeTag,
MDNode *NoAliasTag) {
+ assert((Align == 0 || isPowerOf2_32(Align)) && "Must be 0 or a power of 2");
Dst = getCastedInt8PtrValue(Dst);
Src = getCastedInt8PtrValue(Src);
-
- Value *Ops[] = { Dst, Src, Size, getInt32(Align), getInt1(isVolatile) };
+
+ Value *Ops[] = {Dst, Src, Size, getInt1(isVolatile)};
Type *Tys[] = { Dst->getType(), Src->getType(), Size->getType() };
Module *M = BB->getParent()->getParent();
Value *TheFn = Intrinsic::getDeclaration(M, Intrinsic::memmove, Tys);
CallInst *CI = createCallHelper(TheFn, Ops, this);
-
+
+ auto *MMI = cast<MemMoveInst>(CI);
+ if (Align > 0)
+ MMI->setAlignment(Align);
+
// Set the TBAA info if present.
if (TBAATag)
CI->setMetadata(LLVMContext::MD_tbaa, TBAATag);
diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index f7775be..b73f9df 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -4048,18 +4048,23 @@
case Intrinsic::memcpy:
case Intrinsic::memmove:
case Intrinsic::memset: {
- ConstantInt *AlignCI = dyn_cast<ConstantInt>(CS.getArgOperand(3));
- Assert(AlignCI,
- "alignment argument of memory intrinsics must be a constant int",
- CS);
const auto *MI = cast<MemIntrinsic>(CS.getInstruction());
auto IsValidAlignment = [&](unsigned Alignment) -> bool {
return Alignment == 0 || isPowerOf2_32(Alignment);
};
- Assert(IsValidAlignment(MI->getAlignment()),
- "alignment argument of memory intrinsics must be 0 or a power of 2",
+ Assert(IsValidAlignment(MI->getDestAlignment()),
+ "alignment of arg 0 of memory intrinsic must be 0 or a power of 2",
CS);
- Assert(isa<ConstantInt>(CS.getArgOperand(4)),
+ if (const auto *MTI = dyn_cast<MemTransferInst>(MI)) {
+ Assert(IsValidAlignment(MTI->getSourceAlignment()),
+ "alignment of arg 1 of memory intrinsic must be 0 or a power of 2",
+ CS);
+ // TODO: Remove this assert when we enhance IRBuilder API to create
+ // memcpy/memmove with separate source & dest alignments.
+ Assert(MTI->getSourceAlignment() == MTI->getDestAlignment(),
+ "TEMPORARY: source and dest alignments must be the same");
+ }
+ Assert(isa<ConstantInt>(CS.getArgOperand(3)),
"isvolatile argument of memory intrinsics must be a constant int",
CS);
break;