[llvm] r210721 - Teach LoopUnrollPass to respect loop unrolling hints in metadata.
Eli Bendersky
eliben at google.com
Thu Jun 12 11:14:43 PDT 2014
On Wed, Jun 11, 2014 at 9:43 PM, David Blaikie <dblaikie at gmail.com> wrote:
> I think this may've broken some things... a few of our internal tests
> are failing, and one of the GDB tester's tests is segfaulting (
> http://lab.llvm.org:8011/builders/clang-x86_64-ubuntu-gdb-75/builds/15423
> ) - mind taking a look/reverting? Let me know if you'd like more
> specific reproductions, steps, etc.
>
Reverted in r210807; looking at the failures.
Eli
>
> On Wed, Jun 11, 2014 at 4:15 PM, Eli Bendersky <eliben at google.com> wrote:
> > Author: eliben
> > Date: Wed Jun 11 18:15:35 2014
> > New Revision: 210721
> >
> > URL: http://llvm.org/viewvc/llvm-project?rev=210721&view=rev
> > Log:
> > Teach LoopUnrollPass to respect loop unrolling hints in metadata.
> >
> > See http://reviews.llvm.org/D4090 for more details.
> >
> > The Clang change that produces this metadata was committed in r210667
> >
> > Patch by Mark Heffernan.
> >
> >
> > Added:
> > llvm/trunk/test/Transforms/LoopUnroll/unroll-pragmas.ll
> > Modified:
> > llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp
> >
> > Modified: llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp
> > URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp?rev=210721&r1=210720&r2=210721&view=diff
> >
> ==============================================================================
> > --- llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp (original)
> > +++ llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp Wed Jun 11
> 18:15:35 2014
> > @@ -20,6 +20,7 @@
> > #include "llvm/IR/DataLayout.h"
> > #include "llvm/IR/Dominators.h"
> > #include "llvm/IR/IntrinsicInst.h"
> > +#include "llvm/IR/Metadata.h"
> > #include "llvm/Support/CommandLine.h"
> > #include "llvm/Support/Debug.h"
> > #include "llvm/Support/raw_ostream.h"
> > @@ -36,7 +37,8 @@ UnrollThreshold("unroll-threshold", cl::
> >
> > static cl::opt<unsigned>
> > UnrollCount("unroll-count", cl::init(0), cl::Hidden,
> > - cl::desc("Use this unroll count for all loops, for testing
> purposes"));
> > + cl::desc("Use this unroll count for all loops including those with "
> > + "unroll_count pragma values, for testing purposes"));
> >
> > static cl::opt<bool>
> > UnrollAllowPartial("unroll-allow-partial", cl::init(false), cl::Hidden,
> > @@ -47,6 +49,13 @@ static cl::opt<bool>
> > UnrollRuntime("unroll-runtime", cl::ZeroOrMore, cl::init(false),
> cl::Hidden,
> > cl::desc("Unroll loops with run-time trip counts"));
> >
> > +// Maximum allowed unroll count for a loop being fully unrolled
> > +// because of a pragma unroll(enable) statement (ie, metadata
> > +// "llvm.loopunroll.enable" is true). This prevents unexpected
> > +// behavior like crashing when using this pragma on high trip count
> > +// loops.
> > +static const unsigned PragmaFullUnrollCountLimit = 1024;
> > +
> > namespace {
> > class LoopUnroll : public LoopPass {
> > public:
> > @@ -151,6 +160,63 @@ static unsigned ApproximateLoopSize(cons
> > return LoopSize;
> > }
> >
> > +// Returns the value associated with the given metadata node name (for
> > +// example, "llvm.loopunroll.count"). If no such named metadata node
> > +// exists, then nullptr is returned.
> > +static const ConstantInt *GetUnrollMetadataValue(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())) {
> > + assert(MD->getNumOperands() == 2 &&
> > + "Unroll hint metadata should have two operands.");
> > + return cast<ConstantInt>(MD->getOperand(1));
> > + }
> > + }
> > + return nullptr;
> > +}
> > +
> > +// Returns true if the loop has an unroll(enable) pragma.
> > +static bool HasUnrollEnablePragma(const Loop *L) {
> > + const ConstantInt *EnableValue =
> > + GetUnrollMetadataValue(L, "llvm.loopunroll.enable");
> > + return (EnableValue && EnableValue->getZExtValue());
> > + return false;
> > +}
> > +
> > +// Returns true if the loop has an unroll(disable) pragma.
> > +static bool HasUnrollDisablePragma(const Loop *L) {
> > + const ConstantInt *EnableValue =
> > + GetUnrollMetadataValue(L, "llvm.loopunroll.enable");
> > + return (EnableValue && !EnableValue->getZExtValue());
> > + return false;
> > +}
> > +
> > +// Check for unroll_count(N) pragma. If found, return true and set
> > +// Count to the integer parameter of the pragma.
> > +static bool HasUnrollCountPragma(const Loop *L, int &Count) {
> > + const ConstantInt *CountValue =
> > + GetUnrollMetadataValue(L, "llvm.loopunroll.count");
> > + if (CountValue) {
> > + Count = CountValue->getZExtValue();
> > + assert(Count >= 1 && "Unroll count must be positive.");
> > + return true;
> > + }
> > + return false;
> > +}
> > +
> > bool LoopUnroll::runOnLoop(Loop *L, LPPassManager &LPM) {
> > if (skipOptnoneFunction(L))
> > return false;
> > @@ -202,12 +268,49 @@ bool LoopUnroll::runOnLoop(Loop *L, LPPa
> > TripMultiple = SE->getSmallConstantTripMultiple(L, LatchBlock);
> > }
> >
> > - bool Runtime = UserRuntime ? CurrentRuntime : UP.Runtime;
> > + // User-specified count (either as a command-line option or
> > + // constructor parameter) has highest precedence.
> > + unsigned Count = UserCount ? CurrentCount : 0;
> > +
> > + // If there is no user-specified count, unroll pragmas have the next
> > + // highest precendence.
> > + if (Count == 0) {
> > + if (HasUnrollDisablePragma(L)) {
> > + // Loop has unroll(disable) pragma.
> > + return false;
> > + }
> >
> > - // Use a default unroll-count if the user doesn't specify a value
> > - // and the trip count is a run-time value. The default is different
> > - // for run-time or compile-time trip count loops.
> > - unsigned Count = UserCount ? CurrentCount : UP.Count;
> > + int PragmaCount;
> > + if (HasUnrollCountPragma(L, PragmaCount)) {
> > + if (PragmaCount == 1) {
> > + // Nothing to do.
> > + return false;
> > + }
> > + Count = PragmaCount;
> > + Threshold = NoThreshold;
> > + } else if (HasUnrollEnablePragma(L)) {
> > + // Loop has unroll(enable) pragma without a unroll_count pragma,
> > + // so unroll loop fully if possible.
> > + if (TripCount == 0) {
> > + DEBUG(dbgs() << " Loop has unroll(enable) pragma but loop
> cannot be "
> > + "fully unrolled because trip count is
> unknown.\n");
> > + // Continue with standard heuristic unrolling.
> > + } else if (TripCount > PragmaFullUnrollCountLimit) {
> > + DEBUG(dbgs() << " Loop has unroll(enable) pragma but loop
> cannot be "
> > + "fully unrolled because loop count is greater
> than "
> > + << PragmaFullUnrollCountLimit);
> > + // Continue with standard heuristic unrolling.
> > + } else {
> > + Count = TripCount;
> > + Threshold = NoThreshold;
> > + }
> > + }
> > + }
> > +
> > + if (Count == 0)
> > + Count = UP.Count;
> > +
> > + bool Runtime = UserRuntime ? CurrentRuntime : UP.Runtime;
> > if (Runtime && Count == 0 && TripCount == 0)
> > Count = UnrollRuntimeCount;
> >
> >
> > Added: llvm/trunk/test/Transforms/LoopUnroll/unroll-pragmas.ll
> > URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/unroll-pragmas.ll?rev=210721&view=auto
> >
> ==============================================================================
> > --- llvm/trunk/test/Transforms/LoopUnroll/unroll-pragmas.ll (added)
> > +++ llvm/trunk/test/Transforms/LoopUnroll/unroll-pragmas.ll Wed Jun 11
> 18:15:35 2014
> > @@ -0,0 +1,285 @@
> > +; RUN: opt < %s -loop-unroll -S | FileCheck %s
> > +
> > +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
> > +target triple = "x86_64-unknown-linux-gnu"
> > +
> > +; loop4 contains a small loop which should be completely unrolled by
> > +; the default unrolling heuristics. It serves as a control for the
> > +; unroll(disable) pragma test loop4_with_disable.
> > +;
> > +; CHECK-LABEL: @loop4(
> > +; CHECK-NOT: br i1
> > +define void @loop4(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* %a, i64 %indvars.iv
> > + %0 = load 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, 4
> > + br i1 %exitcond, label %for.end, label %for.body
> > +
> > +for.end: ; preds = %for.body
> > + ret void
> > +}
> > +
> > +; #pragma clang loop unroll(disable)
> > +;
> > +; CHECK-LABEL: @loop4_with_disable(
> > +; CHECK: store i32
> > +; CHECK-NOT: store i32
> > +; CHECK: br i1
> > +define void @loop4_with_disable(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* %a, i64 %indvars.iv
> > + %0 = load 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, 4
> > + br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !1
> > +
> > +for.end: ; preds = %for.body
> > + ret void
> > +}
> > +!1 = metadata !{metadata !1, metadata !2}
> > +!2 = metadata !{metadata !"llvm.loopunroll.enable", i1 false}
> > +
> > +; loop64 has a high enough count that it should *not* be unrolled by
> > +; the default unrolling heuristic. It serves as the control for the
> > +; unroll(enable) pragma test loop64_with_.* tests below.
> > +;
> > +; CHECK-LABEL: @loop64(
> > +; CHECK: store i32
> > +; CHECK-NOT: store i32
> > +; CHECK: br i1
> > +define void @loop64(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* %a, i64 %indvars.iv
> > + %0 = load 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
> > +}
> > +
> > +; #pragma clang loop unroll(enable)
> > +; Loop should be fully unrolled.
> > +;
> > +; CHECK-LABEL: @loop64_with_enable(
> > +; CHECK-NOT: br i1
> > +define void @loop64_with_enable(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* %a, i64 %indvars.iv
> > + %0 = load 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, !llvm.loop !3
> > +
> > +for.end: ; preds = %for.body
> > + ret void
> > +}
> > +!3 = metadata !{metadata !3, metadata !4}
> > +!4 = metadata !{metadata !"llvm.loopunroll.enable", i1 true}
> > +
> > +; #pragma clang loop unroll_count(4)
> > +; Loop should be unrolled 4 times.
> > +;
> > +; CHECK-LABEL: @loop64_with_count4(
> > +; CHECK: store i32
> > +; CHECK: store i32
> > +; CHECK: store i32
> > +; CHECK: store i32
> > +; CHECK-NOT: store i32
> > +; CHECK: br i1
> > +define void @loop64_with_count4(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* %a, i64 %indvars.iv
> > + %0 = load 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, !llvm.loop !5
> > +
> > +for.end: ; preds = %for.body
> > + ret void
> > +}
> > +!5 = metadata !{metadata !5, metadata !6}
> > +!6 = metadata !{metadata !"llvm.loopunroll.count", i32 4}
> > +
> > +
> > +; #pragma clang loop unroll_count(enable) unroll_count(4)
> > +; Loop should be unrolled 4 times.
> > +;
> > +; CHECK-LABEL: @loop64_with_enable_and_count4(
> > +; CHECK: store i32
> > +; CHECK: store i32
> > +; CHECK: store i32
> > +; CHECK: store i32
> > +; CHECK-NOT: store i32
> > +; CHECK: br i1
> > +define void @loop64_with_enable_and_count4(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* %a, i64 %indvars.iv
> > + %0 = load 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, !llvm.loop !7
> > +
> > +for.end: ; preds = %for.body
> > + ret void
> > +}
> > +!7 = metadata !{metadata !7, metadata !6, metadata !4}
> > +
> > +; #pragma clang loop unroll_count(enable)
> > +; Full unrolling is requested, but loop has a dynamic trip count so
> > +; no unrolling should occur.
> > +;
> > +; CHECK-LABEL: @dynamic_loop_with_enable(
> > +; CHECK: store i32
> > +; CHECK-NOT: store i32
> > +; CHECK: br i1
> > +define void @dynamic_loop_with_enable(i32* nocapture %a, i32 %b) {
> > +entry:
> > + %cmp3 = icmp sgt i32 %b, 0
> > + br i1 %cmp3, label %for.body, label %for.end, !llvm.loop !8
> > +
> > +for.body: ; preds = %entry,
> %for.body
> > + %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %entry ]
> > + %arrayidx = getelementptr inbounds i32* %a, i64 %indvars.iv
> > + %0 = load 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
> > + %lftr.wideiv = trunc i64 %indvars.iv.next to i32
> > + %exitcond = icmp eq i32 %lftr.wideiv, %b
> > + br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !8
> > +
> > +for.end: ; preds = %for.body,
> %entry
> > + ret void
> > +}
> > +!8 = metadata !{metadata !8, metadata !4}
> > +
> > +; #pragma clang loop unroll_count(4)
> > +; Loop has a dynamic trip count. Unrolling should occur, but no
> > +; conditional branches can be removed.
> > +;
> > +; CHECK-LABEL: @dynamic_loop_with_count4(
> > +; CHECK-NOT: store
> > +; CHECK: br i1
> > +; CHECK: store
> > +; CHECK: br i1
> > +; CHECK: store
> > +; CHECK: br i1
> > +; CHECK: store
> > +; CHECK: br i1
> > +; CHECK: store
> > +; CHECK: br i1
> > +; CHECK-NOT: br i1
> > +define void @dynamic_loop_with_count4(i32* nocapture %a, i32 %b) {
> > +entry:
> > + %cmp3 = icmp sgt i32 %b, 0
> > + br i1 %cmp3, label %for.body, label %for.end, !llvm.loop !9
> > +
> > +for.body: ; preds = %entry,
> %for.body
> > + %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %entry ]
> > + %arrayidx = getelementptr inbounds i32* %a, i64 %indvars.iv
> > + %0 = load 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
> > + %lftr.wideiv = trunc i64 %indvars.iv.next to i32
> > + %exitcond = icmp eq i32 %lftr.wideiv, %b
> > + br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !9
> > +
> > +for.end: ; preds = %for.body,
> %entry
> > + ret void
> > +}
> > +!9 = metadata !{metadata !9, metadata !6}
> > +
> > +; #pragma clang loop unroll_count(1)
> > +; Loop should not be unrolled
> > +;
> > +; CHECK-LABEL: @unroll_1(
> > +; CHECK: store i32
> > +; CHECK-NOT: store i32
> > +; CHECK: br i1
> > +define void @unroll_1(i32* nocapture %a, i32 %b) {
> > +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* %a, i64 %indvars.iv
> > + %0 = load 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, 4
> > + br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !10
> > +
> > +for.end: ; preds = %for.body
> > + ret void
> > +}
> > +!10 = metadata !{metadata !10, metadata !11}
> > +!11 = metadata !{metadata !"llvm.loopunroll.count", i32 1}
> > +
> > +; #pragma clang loop unroll(enable)
> > +; Loop has very high loop count (1 million) and full unrolling was
> requested.
> > +; Loop should not be unrolled.
> > +;
> > +; CHECK-LABEL: @unroll_1M(
> > +; CHECK: store i32
> > +; CHECK-NOT: store i32
> > +; CHECK: br i1
> > +define void @unroll_1M(i32* nocapture %a, i32 %b) {
> > +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* %a, i64 %indvars.iv
> > + %0 = load 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, 1000000
> > + br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !12
> > +
> > +for.end: ; preds = %for.body
> > + ret void
> > +}
> > +!12 = metadata !{metadata !12, metadata !4}
> >
> >
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20140612/89fa62f0/attachment.html>
More information about the llvm-commits
mailing list