1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
|
// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#include <vector>
#include <set>
#include "rustllvm.h"
#if LLVM_VERSION_GE(5, 0)
#include "llvm/IR/CallSite.h"
#include "llvm/IR/Module.h"
#include "llvm/ADT/STLExtras.h"
using namespace llvm;
static std::vector<Function*>
GetFunctionsWithSimdArgs(Module *M) {
std::vector<Function*> Ret;
for (auto &F : M->functions()) {
// Skip all intrinsic calls as these are always tightly controlled to "work
// correctly", so no need to fixup any of these.
if (F.isIntrinsic())
continue;
// We're only interested in rustc-defined functions, not unstably-defined
// imported SIMD ffi functions.
if (F.isDeclaration())
continue;
// Argument promotion only happens on internal functions, so skip demoting
// arguments in external functions like FFI shims and such.
if (!F.hasLocalLinkage())
continue;
// If any argument to this function is a by-value vector type, then that's
// bad! The compiler didn't generate any functions that looked like this,
// and we try to rely on LLVM to not do this! Argument promotion may,
// however, promote arguments from behind references. In any case, figure
// out if we're interested in demoting this argument.
if (any_of(F.args(), [](Argument &arg) { return arg.getType()->isVectorTy(); }))
Ret.push_back(&F);
}
return Ret;
}
extern "C" void
LLVMRustDemoteSimdArguments(LLVMModuleRef Mod) {
Module *M = unwrap(Mod);
auto Functions = GetFunctionsWithSimdArgs(M);
for (auto F : Functions) {
// Build up our list of new parameters and new argument attributes.
// We're only changing those arguments which are vector types.
SmallVector<Type*, 8> Params;
SmallVector<AttributeSet, 8> ArgAttrVec;
auto PAL = F->getAttributes();
for (auto &Arg : F->args()) {
auto *Ty = Arg.getType();
if (Ty->isVectorTy()) {
Params.push_back(PointerType::get(Ty, 0));
ArgAttrVec.push_back(AttributeSet());
} else {
Params.push_back(Ty);
ArgAttrVec.push_back(PAL.getParamAttributes(Arg.getArgNo()));
}
}
// Replace `F` with a new function with our new signature. I'm... not really
// sure how this works, but this is all the steps `ArgumentPromotion` does
// to replace a signature as well.
assert(!F->isVarArg()); // ArgumentPromotion should skip these fns
FunctionType *NFTy = FunctionType::get(F->getReturnType(), Params, false);
Function *NF = Function::Create(NFTy, F->getLinkage(), F->getName());
NF->copyAttributesFrom(F);
NF->setSubprogram(F->getSubprogram());
F->setSubprogram(nullptr);
NF->setAttributes(AttributeList::get(F->getContext(),
PAL.getFnAttributes(),
PAL.getRetAttributes(),
ArgAttrVec));
ArgAttrVec.clear();
F->getParent()->getFunctionList().insert(F->getIterator(), NF);
NF->takeName(F);
// Iterate over all invocations of `F`, updating all `call` instructions to
// store immediate vector types in a local `alloc` instead of a by-value
// vector.
//
// Like before, much of this is copied from the `ArgumentPromotion` pass in
// LLVM.
SmallVector<Value*, 16> Args;
while (!F->use_empty()) {
CallSite CS(F->user_back());
assert(CS.getCalledFunction() == F);
Instruction *Call = CS.getInstruction();
const AttributeList &CallPAL = CS.getAttributes();
// Loop over the operands, inserting an `alloca` and a store for any
// argument we're demoting to be by reference
//
// FIXME: we probably want to figure out an LLVM pass to run and clean up
// this function and instructions we're generating, we should in theory
// only generate a maximum number of `alloca` instructions rather than
// one-per-variable unconditionally.
CallSite::arg_iterator AI = CS.arg_begin();
size_t ArgNo = 0;
for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E;
++I, ++AI, ++ArgNo) {
if (I->getType()->isVectorTy()) {
AllocaInst *AllocA = new AllocaInst(I->getType(), 0, nullptr, "", Call);
new StoreInst(*AI, AllocA, Call);
Args.push_back(AllocA);
ArgAttrVec.push_back(AttributeSet());
} else {
Args.push_back(*AI);
ArgAttrVec.push_back(CallPAL.getParamAttributes(ArgNo));
}
}
assert(AI == CS.arg_end());
// Create a new call instructions which we'll use to replace the old call
// instruction, copying over as many attributes and such as possible.
SmallVector<OperandBundleDef, 1> OpBundles;
CS.getOperandBundlesAsDefs(OpBundles);
CallSite NewCS;
if (InvokeInst *II = dyn_cast<InvokeInst>(Call)) {
InvokeInst::Create(NF, II->getNormalDest(), II->getUnwindDest(),
Args, OpBundles, "", Call);
} else {
auto *NewCall = CallInst::Create(NF, Args, OpBundles, "", Call);
NewCall->setTailCallKind(cast<CallInst>(Call)->getTailCallKind());
NewCS = NewCall;
}
NewCS.setCallingConv(CS.getCallingConv());
NewCS.setAttributes(
AttributeList::get(F->getContext(), CallPAL.getFnAttributes(),
CallPAL.getRetAttributes(), ArgAttrVec));
NewCS->setDebugLoc(Call->getDebugLoc());
Args.clear();
ArgAttrVec.clear();
Call->replaceAllUsesWith(NewCS.getInstruction());
NewCS->takeName(Call);
Call->eraseFromParent();
}
// Splice the body of the old function right into the new function.
NF->getBasicBlockList().splice(NF->begin(), F->getBasicBlockList());
// Update our new function to replace all uses of the by-value argument with
// loads of the pointer argument we've generated.
//
// FIXME: we probably want to only generate one load instruction per
// function? Or maybe run an LLVM pass to clean up this function?
for (Function::arg_iterator I = F->arg_begin(),
E = F->arg_end(),
I2 = NF->arg_begin();
I != E;
++I, ++I2) {
if (I->getType()->isVectorTy()) {
I->replaceAllUsesWith(new LoadInst(&*I2, "", &NF->begin()->front()));
} else {
I->replaceAllUsesWith(&*I2);
}
I2->takeName(&*I);
}
// Delete all references to the old function, it should be entirely dead
// now.
M->getFunctionList().remove(F);
}
}
#else // LLVM_VERSION_GE(8, 0)
extern "C" void
LLVMRustDemoteSimdArguments(LLVMModuleRef Mod) {
}
#endif // LLVM_VERSION_GE(8, 0)
|
