[llvm] r210721 - Teach LoopUnrollPass to respect loop unrolling hints in metadata.

David Blaikie dblaikie at gmail.com
Thu Jun 12 11:15:37 PDT 2014


On Thu, Jun 12, 2014 at 8:22 AM, Eli Bendersky <eliben at google.com> wrote:
> 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
>> ) -
>
>
> This one has a rather long blamelist - any reason to believe it was r210721
> that causes the failures?

A rather shorter (only this commit) blame list on our internal
infrastructure, which I've cc'd you on.

>
>>
>> mind taking a look/reverting?
>
>
>
>>
>> Let me know if you'd like more
>> specific reproductions, steps, etc.
>
>
> Yes, please.

If you'd like to start with the public reproduction, checkout the
clang-tests-external repository, configure and build gdb, then run the
test suite:

make -k -j6 check 'RUNTESTFLAGS=CC_FOR_TARGET=clang
CXX_FOR_TARGET=clang++ CFLAGS_FOR_TARGET="-w -fno-limit-debug-info"'

(hmm, looks like we might not actually be running tests in parallel -
I should fix that, could reduce blame lists by a bit... )

You can run a specific test like this, I think:

make -k -j6 check 'RUNTESTFLAGS=CC_FOR_TARGET=clang
CXX_FOR_TARGET=clang++ CFLAGS_FOR_TARGET="-w -fno-limit-debug-info"
gdb.base/call-ar-st.exp'




>
> 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
>
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