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The patch set unroll disable pragma when unroll 

with user specified count has been applied.

Summary:
Previously SetLoopAlreadyUnrolled() set the disable pragma only if
there was some loop metadata.
Now it set the pragma in all cases. This helps to prevent multiple
unroll when -unroll-count=N is given.

Reviewers: mzolotukhin

Differential Revision: http://reviews.llvm.org/D20765

From: Evgeny Stupachenko <evstupac@gmail.com>
llvm-svn: 272195
This commit is contained in:
Evgeny Stupachenko 2016-06-08 20:21:24 +00:00
parent 572135f717
commit 3e2f389a7e
2 changed files with 36 additions and 11 deletions
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22
llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
View File

@ -604,22 +604,22 @@ static unsigned UnrollCountPragmaValue(const Loop *L) {
// unrolling pass is run more than once (which it generally is).
static void SetLoopAlreadyUnrolled(Loop *L) {
MDNode *LoopID = L->getLoopID();
if (!LoopID)
return;
// First remove any existing loop unrolling metadata.
SmallVector<Metadata *, 4> MDs;
// Reserve first location for self reference to the LoopID metadata node.
MDs.push_back(nullptr);
for (unsigned i = 1, ie = LoopID->getNumOperands(); i < ie; ++i) {
bool IsUnrollMetadata = false;
MDNode *MD = dyn_cast<MDNode>(LoopID->getOperand(i));
if (MD) {
const MDString *S = dyn_cast<MDString>(MD->getOperand(0));
IsUnrollMetadata = S && S->getString().startswith("llvm.loop.unroll.");
if (LoopID) {
for (unsigned i = 1, ie = LoopID->getNumOperands(); i < ie; ++i) {
bool IsUnrollMetadata = false;
MDNode *MD = dyn_cast<MDNode>(LoopID->getOperand(i));
if (MD) {
const MDString *S = dyn_cast<MDString>(MD->getOperand(0));
IsUnrollMetadata = S && S->getString().startswith("llvm.loop.unroll.");
}
if (!IsUnrollMetadata)
MDs.push_back(LoopID->getOperand(i));
}
if (!IsUnrollMetadata)
MDs.push_back(LoopID->getOperand(i));
}
// Add unroll(disable) metadata to disable future unrolling.

25
llvm/test/Transforms/LoopUnroll/unroll-count.ll Normal file
View File

@ -0,0 +1,25 @@
; RUN: opt < %s -S -loop-unroll -unroll-count=2 | FileCheck %s
; Checks that "llvm.loop.unroll.disable" is set when
; unroll with count set by user has been applied.
;
; CHECK-LABEL: @foo(
; CHECK: llvm.loop.unroll.disable
define void @foo(i32* nocapture %a) {
entry:
br label %for.body
for.body: ; preds = %for.body, %entry
%indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
%arrayidx = getelementptr inbounds i32, i32* %a, i64 %indvars.iv
%0 = load i32, i32* %arrayidx, align 4
%inc = add nsw i32 %0, 1
store i32 %inc, i32* %arrayidx, align 4
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%exitcond = icmp eq i64 %indvars.iv.next, 64
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body
ret void
}