mirror of
https://github.com/c64scene-ar/llvm-6502.git
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[NVPTX] convert pointers in byval kernel arguments to global
Summary:
For example, in
struct S {
int *x;
int *y;
};
__global__ void foo(S s) {
int *b = s.y;
// use b
}
"b" is guaranteed to point to global. NVPTX should emit ld.global/st.global for
accessing "b".
Reviewers: jholewinski
Subscribers: llvm-commits, jholewinski
Differential Revision: http://reviews.llvm.org/D11505
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@243790 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jingyue Wu
parent
be031d9158
commit
bd11ccb2b9
@ -47,6 +47,36 @@
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// ...
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// }
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//
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// 3. Convert pointers in a byval kernel parameter to pointers in the global
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// address space. As #2, it allows NVPTX to emit more ld/st.global. E.g.,
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//
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// struct S {
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// int *x;
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// int *y;
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// };
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// __global__ void foo(S s) {
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// int *b = s.y;
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// // use b
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// }
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//
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// "b" points to the global address space. In the IR level,
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//
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// define void @foo({i32*, i32*}* byval %input) {
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// %b_ptr = getelementptr {i32*, i32*}, {i32*, i32*}* %input, i64 0, i32 1
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// %b = load i32*, i32** %b_ptr
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// ; use %b
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// }
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//
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// becomes
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//
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// define void @foo({i32*, i32*}* byval %input) {
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// %b_ptr = getelementptr {i32*, i32*}, {i32*, i32*}* %input, i64 0, i32 1
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// %b = load i32*, i32** %b_ptr
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// %b_global = addrspacecast i32* %b to i32 addrspace(1)*
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// %b_generic = addrspacecast i32 addrspace(1)* %b_global to i32*
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// ; use %b_generic
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// }
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//
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// TODO: merge this pass with NVPTXFavorNonGenericAddrSpace so that other passes
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// don't cancel the addrspacecast pair this pass emits.
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//===----------------------------------------------------------------------===//
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@ -54,6 +84,7 @@
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#include "NVPTX.h"
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#include "NVPTXUtilities.h"
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#include "NVPTXTargetMachine.h"
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#include "llvm/Analysis/ValueTracking.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/Module.h"
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@ -71,9 +102,12 @@ class NVPTXLowerKernelArgs : public FunctionPass {
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bool runOnFunction(Function &F) override;
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// handle byval parameters
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void handleByValParam(Argument *);
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// handle non-byval pointer parameters
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void handlePointerParam(Argument *);
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void handleByValParam(Argument *Arg);
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// Knowing Ptr must point to the global address space, this function
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// addrspacecasts Ptr to global and then back to generic. This allows
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// NVPTXFavorNonGenericAddrSpace to fold the global-to-generic cast into
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// loads/stores that appear later.
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void markPointerAsGlobal(Value *Ptr);
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public:
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static char ID; // Pass identification, replacement for typeid
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@ -128,26 +162,33 @@ void NVPTXLowerKernelArgs::handleByValParam(Argument *Arg) {
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new StoreInst(LI, AllocA, FirstInst);
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}
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void NVPTXLowerKernelArgs::handlePointerParam(Argument *Arg) {
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assert(!Arg->hasByValAttr() &&
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"byval params should be handled by handleByValParam");
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// Do nothing if the argument already points to the global address space.
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if (Arg->getType()->getPointerAddressSpace() == ADDRESS_SPACE_GLOBAL)
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void NVPTXLowerKernelArgs::markPointerAsGlobal(Value *Ptr) {
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if (Ptr->getType()->getPointerAddressSpace() == ADDRESS_SPACE_GLOBAL)
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return;
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Instruction *FirstInst = Arg->getParent()->getEntryBlock().begin();
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Instruction *ArgInGlobal = new AddrSpaceCastInst(
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Arg, PointerType::get(Arg->getType()->getPointerElementType(),
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ADDRESS_SPACE_GLOBAL),
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Arg->getName(), FirstInst);
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Value *ArgInGeneric = new AddrSpaceCastInst(ArgInGlobal, Arg->getType(),
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Arg->getName(), FirstInst);
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// Replace with ArgInGeneric all uses of Args except ArgInGlobal.
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Arg->replaceAllUsesWith(ArgInGeneric);
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ArgInGlobal->setOperand(0, Arg);
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// Deciding where to emit the addrspacecast pair.
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BasicBlock::iterator InsertPt;
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if (Argument *Arg = dyn_cast<Argument>(Ptr)) {
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// Insert at the functon entry if Ptr is an argument.
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InsertPt = Arg->getParent()->getEntryBlock().begin();
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} else {
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// Insert right after Ptr if Ptr is an instruction.
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InsertPt = cast<Instruction>(Ptr);
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++InsertPt;
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assert(InsertPt != InsertPt->getParent()->end() &&
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"We don't call this function with Ptr being a terminator.");
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}
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Instruction *PtrInGlobal = new AddrSpaceCastInst(
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Ptr, PointerType::get(Ptr->getType()->getPointerElementType(),
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ADDRESS_SPACE_GLOBAL),
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Ptr->getName(), InsertPt);
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Value *PtrInGeneric = new AddrSpaceCastInst(PtrInGlobal, Ptr->getType(),
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Ptr->getName(), InsertPt);
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// Replace with PtrInGeneric all uses of Ptr except PtrInGlobal.
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Ptr->replaceAllUsesWith(PtrInGeneric);
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PtrInGlobal->setOperand(0, Ptr);
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}
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// =============================================================================
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// Main function for this pass.
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@ -157,12 +198,32 @@ bool NVPTXLowerKernelArgs::runOnFunction(Function &F) {
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if (!isKernelFunction(F))
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return false;
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if (TM && TM->getDrvInterface() == NVPTX::CUDA) {
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// Mark pointers in byval structs as global.
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for (auto &B : F) {
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for (auto &I : B) {
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if (LoadInst *LI = dyn_cast<LoadInst>(&I)) {
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if (LI->getType()->isPointerTy()) {
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Value *UO = GetUnderlyingObject(LI->getPointerOperand(),
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F.getParent()->getDataLayout());
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if (Argument *Arg = dyn_cast<Argument>(UO)) {
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if (Arg->hasByValAttr()) {
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// LI is a load from a pointer within a byval kernel parameter.
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markPointerAsGlobal(LI);
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}
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}
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}
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}
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}
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}
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}
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for (Argument &Arg : F.args()) {
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if (Arg.getType()->isPointerTy()) {
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if (Arg.hasByValAttr())
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handleByValParam(&Arg);
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else if (TM && TM->getDrvInterface() == NVPTX::CUDA)
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handlePointerParam(&Arg);
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markPointerAsGlobal(&Arg);
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}
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}
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return true;
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@ -1,7 +1,7 @@
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; RUN: llc < %s -march=nvptx64 -mcpu=sm_20 | FileCheck %s
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target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v16:16:16-v32:32:32-v64:64:64-v128:128:128-n16:32:64"
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target triple = "nvptx64-unknown-unknown"
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target triple = "nvptx64-nvidia-cuda"
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; Verify that both %input and %output are converted to global pointers and then
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; addrspacecast'ed back to the original type.
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@ -26,6 +26,22 @@ define void @kernel2(float addrspace(1)* %input, float addrspace(1)* %output) {
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ret void
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}
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!nvvm.annotations = !{!0, !1}
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%struct.S = type { i32*, i32* }
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define void @ptr_in_byval(%struct.S* byval %input, i32* %output) {
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; CHECK-LABEL: .visible .entry ptr_in_byval(
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; CHECK: cvta.to.global.u64
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; CHECK: cvta.to.global.u64
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%b_ptr = getelementptr inbounds %struct.S, %struct.S* %input, i64 0, i32 1
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%b = load i32*, i32** %b_ptr, align 4
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%v = load i32, i32* %b, align 4
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; CHECK: ld.global.u32
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store i32 %v, i32* %output, align 4
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; CHECK: st.global.u32
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ret void
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}
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!nvvm.annotations = !{!0, !1, !2}
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!0 = !{void (float*, float*)* @kernel, !"kernel", i32 1}
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!1 = !{void (float addrspace(1)*, float addrspace(1)*)* @kernel2, !"kernel", i32 1}
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!2 = !{void (%struct.S*, i32*)* @ptr_in_byval, !"kernel", i32 1}
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