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[NVPTX] Order global variables in def-use order before emiting them in the final assembly 

llvm-svn: 168198
This commit is contained in:
Justin Holewinski 2012-11-16 21:03:51 +00:00
parent 898a0a02bb
commit 2c5ac70dd9
2 changed files with 87 additions and 3 deletions
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70
llvm/lib/Target/NVPTX/NVPTXAsmPrinter.cpp
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@ -68,7 +68,54 @@ static cl::opt<bool, true>InterleaveSrc("nvptx-emit-src",
cl::location(llvm::InterleaveSrcInPtx));
namespace {
/// DiscoverDependentGlobals - Return a set of GlobalVariables on which \p V
/// depends.
void DiscoverDependentGlobals(Value *V,
DenseSet<GlobalVariable*> &Globals) {
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
Globals.insert(GV);
else {
if (User *U = dyn_cast<User>(V)) {
for (unsigned i = 0, e = U->getNumOperands(); i != e; ++i) {
DiscoverDependentGlobals(U->getOperand(i), Globals);
}
}
}
}
/// VisitGlobalVariableForEmission - Add \p GV to the list of GlobalVariable
/// instances to be emitted, but only after any dependents have been added
/// first.
void VisitGlobalVariableForEmission(GlobalVariable *GV,
SmallVectorImpl<GlobalVariable*> &Order,
DenseSet<GlobalVariable*> &Visited,
DenseSet<GlobalVariable*> &Visiting) {
// Have we already visited this one?
if (Visited.count(GV)) return;
// Do we have a circular dependency?
if (Visiting.count(GV))
report_fatal_error("Circular dependency found in global variable set");
// Start visiting this global
Visiting.insert(GV);
// Make sure we visit all dependents first
DenseSet<GlobalVariable*> Others;
for (unsigned i = 0, e = GV->getNumOperands(); i != e; ++i)
DiscoverDependentGlobals(GV->getOperand(i), Others);
for (DenseSet<GlobalVariable*>::iterator I = Others.begin(),
E = Others.end(); I != E; ++I)
VisitGlobalVariableForEmission(*I, Order, Visited, Visiting);
// Now we can visit ourself
Order.push_back(GV);
Visited.insert(GV);
Visiting.erase(GV);
}
}
// @TODO: This is a copy from AsmPrinter.cpp. The function is static, so we
// cannot just link to the existing version.
@ -893,10 +940,27 @@ bool NVPTXAsmPrinter::doInitialization (Module &M) {
emitDeclarations(M, OS2);
// Print out module-level global variables here.
// As ptxas does not support forward references of globals, we need to first
// sort the list of module-level globals in def-use order. We visit each
// global variable in order, and ensure that we emit it *after* its dependent
// globals. We use a little extra memory maintaining both a set and a list to
// have fast searches while maintaining a strict ordering.
SmallVector<GlobalVariable*,8> Globals;
DenseSet<GlobalVariable*> GVVisited;
DenseSet<GlobalVariable*> GVVisiting;
// Visit each global variable, in order
for (Module::global_iterator I = M.global_begin(), E = M.global_end();
I != E; ++I)
printModuleLevelGV(I, OS2);
I != E; ++I)
VisitGlobalVariableForEmission(I, Globals, GVVisited, GVVisiting);
assert(GVVisited.size() == M.getGlobalList().size() &&
"Missed a global variable");
assert(GVVisiting.size() == 0 && "Did not fully process a global variable");
// Print out module-level global variables in proper order
for (unsigned i = 0, e = Globals.size(); i != e; ++i)
printModuleLevelGV(Globals[i], OS2);
OS2 << '\n';

20
llvm/test/CodeGen/NVPTX/global-ordering.ll Normal file
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@ -0,0 +1,20 @@
; RUN: llc < %s -march=nvptx -mcpu=sm_20 | FileCheck %s --check-prefix=PTX32
; RUN: llc < %s -march=nvptx64 -mcpu=sm_20 | FileCheck %s --check-prefix=PTX64
; Make sure we emit these globals in def-use order
; PTX32: .visible .global .align 1 .u8 a = 2;
; PTX32-NEXT: .visible .global .align 4 .u32 a2 = a;
; PTX64: .visible .global .align 1 .u8 a = 2;
; PTX64-NEXT: .visible .global .align 8 .u64 a2 = a;
@a2 = addrspace(1) global i8 addrspace(1)* @a
@a = addrspace(1) global i8 2
; PTX32: .visible .global .align 1 .u8 b = 1;
; PTX32-NEXT: .visible .global .align 4 .u32 b2[2] = {b, b};
; PTX64: .visible .global .align 1 .u8 b = 1;
; PTX64-NEXT: .visible .global .align 8 .u64 b2[2] = {b, b};
@b2 = addrspace(1) global [2 x i8 addrspace(1)*] [i8 addrspace(1)* @b, i8 addrspace(1)* @b]
@b = addrspace(1) global i8 1