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[NVPTX] Emit .pragma "nounroll" for loops marked with nounroll

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Summary:
CUDA driver can unroll loops when jit-compiling PTX. To prevent CUDA
driver from unrolling a loop marked with llvm.loop.unroll.disable is not
unrolled by CUDA driver, we need to emit .pragma "nounroll" at the
header of that loop.

This patch also extracts getting unroll metadata from loop ID metadata
into a shared helper function.

Test Plan: test/CodeGen/NVPTX/nounroll.ll

Reviewers: eliben, meheff, jholewinski

Reviewed By: jholewinski

Subscribers: jholewinski, llvm-commits

Differential Revision: http://reviews.llvm.org/D7041

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227703 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jingyue Wu
2015-02-01 02:27:45 +00:00
parent 58e57f1604
commit f15b696b79
7 changed files with 124 additions and 26 deletions
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27
lib/Transforms/Scalar/LoopUnrollPass.cpp
View File

@@ -234,44 +234,27 @@ static unsigned ApproximateLoopSize(const Loop *L, unsigned &NumCalls,
// Returns the loop hint metadata node with the given name (for example,
// "llvm.loop.unroll.count"). If no such metadata node exists, then nullptr is
// returned.
static const MDNode *GetUnrollMetadata(const Loop *L, StringRef Name) {
static const MDNode *GetUnrollMetadataForLoop(const Loop *L, StringRef Name) {
MDNode *LoopID = L->getLoopID();
if (!LoopID)
return nullptr;
// First operand should refer to the loop id itself.
assert(LoopID->getNumOperands() > 0 && "requires at least one operand");
assert(LoopID->getOperand(0) == LoopID && "invalid loop id");
for (unsigned i = 1, e = LoopID->getNumOperands(); i < e; ++i) {
const MDNode *MD = dyn_cast<MDNode>(LoopID->getOperand(i));
if (!MD)
continue;
const MDString *S = dyn_cast<MDString>(MD->getOperand(0));
if (!S)
continue;
if (Name.equals(S->getString()))
return MD;
}
return nullptr;
return GetUnrollMetadata(LoopID, Name);
}
// Returns true if the loop has an unroll(full) pragma.
static bool HasUnrollFullPragma(const Loop *L) {
return GetUnrollMetadata(L, "llvm.loop.unroll.full");
return GetUnrollMetadataForLoop(L, "llvm.loop.unroll.full");
}
// Returns true if the loop has an unroll(disable) pragma.
static bool HasUnrollDisablePragma(const Loop *L) {
return GetUnrollMetadata(L, "llvm.loop.unroll.disable");
return GetUnrollMetadataForLoop(L, "llvm.loop.unroll.disable");
}
// If loop has an unroll_count pragma return the (necessarily
// positive) value from the pragma. Otherwise return 0.
static unsigned UnrollCountPragmaValue(const Loop *L) {
const MDNode *MD = GetUnrollMetadata(L, "llvm.loop.unroll.count");
const MDNode *MD = GetUnrollMetadataForLoop(L, "llvm.loop.unroll.count");
if (MD) {
assert(MD->getNumOperands() == 2 &&
"Unroll count hint metadata should have two operands.");