[ARM] Enable partial and runtime unrolling

Enable runtime and partial loop unrolling of simple loops without
calls on M-class cores. The thresholds are calculated based on
whether the target is Thumb or Thumb-2.

Differential Revision: https://reviews.llvm.org/D34619

llvm-svn: 308956

diff --git a/llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp b/llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp
index 51b0fed..dc222bd 100644 (file)
--- a/llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp
+++ b/llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp
@@ -562,3 +562,35 @@ int ARMTTIImpl::getInterleavedMemoryOpCost(unsigned Opcode, Type *VecTy,
   return BaseT::getInterleavedMemoryOpCost(Opcode, VecTy, Factor, Indices,
                                            Alignment, AddressSpace);
 }
+
+void ARMTTIImpl::getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
+                                         TTI::UnrollingPreferences &UP) {
+  // Only currently enable these preferences for M-Class cores.
+  if (!ST->isMClass() || L->getNumBlocks() != 1)
+    return BasicTTIImplBase::getUnrollingPreferences(L, SE, UP);
+
+  // Disable loop unrolling for Oz and Os.
+  UP.OptSizeThreshold = 0;
+  UP.PartialOptSizeThreshold = 0;
+
+  // Scan the loop: don't unroll loops with calls as this could prevent
+  // inlining.
+  BasicBlock *BB = L->getLoopLatch();
+  for (auto &I : *BB) {
+    if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
+      ImmutableCallSite CS(&I);
+      if (const Function *F = CS.getCalledFunction()) {
+        if (!isLoweredToCall(F))
+          continue;
+      }
+      return;
+    }
+  }
+
+  // Enable partial and runtime unrolling, set the initial threshold based upon
+  // the number of registers available.
+  UP.Partial = true;
+  UP.Runtime = true;
+  UP.Threshold = ST->isThumb1Only() ? 75 : 150;
+  UP.PartialThreshold = ST->isThumb1Only() ? 75 : 150;
+}

diff --git a/llvm/lib/Target/ARM/ARMTargetTransformInfo.h b/llvm/lib/Target/ARM/ARMTargetTransformInfo.h
index 0695a4e..0c94368 100644 (file)
--- a/llvm/lib/Target/ARM/ARMTargetTransformInfo.h
+++ b/llvm/lib/Target/ARM/ARMTargetTransformInfo.h
@@ -158,6 +158,9 @@ public:
                                  ArrayRef<unsigned> Indices, unsigned Alignment,
                                  unsigned AddressSpace);
 
+  void getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
+                               TTI::UnrollingPreferences &UP);
+
   bool shouldBuildLookupTablesForConstant(Constant *C) const {
     // In the ROPI and RWPI relocation models we can't have pointers to global
     // variables or functions in constant data, so don't convert switches to

diff --git a/llvm/test/Transforms/LoopUnroll/ARM/lit.local.cfg b/llvm/test/Transforms/LoopUnroll/ARM/lit.local.cfg
new file mode 100644 (file)
index 0000000..98c6700
--- /dev/null
+++ b/llvm/test/Transforms/LoopUnroll/ARM/lit.local.cfg
@@ -0,0 +1,3 @@
+if not 'ARM' in config.root.targets:
+    config.unsupported = True
+

diff --git a/llvm/test/Transforms/LoopUnroll/ARM/loop-unrolling.ll b/llvm/test/Transforms/LoopUnroll/ARM/loop-unrolling.ll
new file mode 100644 (file)
index 0000000..f2b86ae
--- /dev/null
+++ b/llvm/test/Transforms/LoopUnroll/ARM/loop-unrolling.ll
@@ -0,0 +1,210 @@
+; RUN: opt -mtriple=armv7 -mcpu=cortex-a57 -loop-unroll -S %s -o - | FileCheck %s --check-prefix=CHECK-UNROLL-V7
+; RUN: opt -mtriple=thumbv7 -mcpu=cortex-a57 -loop-unroll -S %s -o - | FileCheck %s --check-prefix=CHECK-UNROLL-V7
+; RUN: opt -mtriple=thumbv8m -mcpu=cortex-m23 -loop-unroll -S %s -o - | FileCheck %s --check-prefix=CHECK-UNROLL-SMALL
+; RUN: opt -mtriple=thumbv7m -mcpu=cortex-m4 -loop-unroll -S %s -o - | FileCheck %s --check-prefix=CHECK-UNROLL
+; RUN: opt -mtriple=thumbv8m.main -mcpu=cortex-m33 -loop-unroll -S %s -o - | FileCheck %s --check-prefix=CHECK-UNROLL
+
+; CHECK-LABEL: partial
+define arm_aapcs_vfpcc void @partial(i32* nocapture %C, i32* nocapture readonly %A, i32* nocapture readonly %B) local_unnamed_addr #0 {
+entry:
+  br label %for.body
+
+; CHECK-LABEL: for.body
+for.body:
+
+; CHECK-UNROLL-V7: [[IV0:%[a-z.0-9]+]] = phi i32 [ 0, %entry ], [ [[IV2:%[a-z.0-9]+]], %for.body ]
+; CHECK-UNROLL-V7: [[IV1:%[a-z.0-9]+]] = add nuw nsw i32 [[IV0]], 1
+; CHECK-UNROLL-V7: [[IV2]] = add nuw nsw i32 [[IV1]], 1
+; CHECK-UNROLL-V7: [[CMP:%[a-z.0-9]+]] = icmp eq i32 [[IV2]], 1024
+; CHECK-UNROLL-V7: br i1 [[CMP]], label [[END:%[a-z.]+]], label %for.body
+
+; CHECK-UNROLL-SMALL: [[IV0:%[a-z.0-9]+]] = phi i32 [ 0, %entry ], [ [[IV8:%[a-z.0-9]+]], %for.body ]
+; CHECK-UNROLL-SMALL: [[IV1:%[a-z.0-9]+]] = add nuw nsw i32 [[IV0]], 1
+; CHECK-UNROLL-SMALL: [[IV2:%[a-z.0-9]+]] = add nuw nsw i32 [[IV1]], 1
+; CHECK-UNROLL-SMALL: [[IV3:%[a-z.0-9]+]] = add nuw nsw i32 [[IV2]], 1
+; CHECK-UNROLL-SMALL: [[IV4:%[a-z.0-9]+]] = add nuw nsw i32 [[IV3]], 1
+; CHECK-UNROLL-SMALL: [[IV5:%[a-z.0-9]+]] = add nuw nsw i32 [[IV4]], 1
+; CHECK-UNROLL-SMALL: [[IV6:%[a-z.0-9]+]] = add nuw nsw i32 [[IV5]], 1
+; CHECK-UNROLL-SMALL: [[IV7:%[a-z.0-9]+]] = add nuw nsw i32 [[IV6]], 1
+; CHECK-UNROLL-SMALL: [[IV8]] = add nuw nsw i32 [[IV7]], 1
+; CHECK-UNROLL-SMALL: [[CMP:%[a-z.0-9]+]] = icmp eq i32 [[IV8]], 1024
+; CHECK-UNROLL-SMALL: br i1 [[CMP]], label [[END:%[a-z.]+]], label %for.body
+
+; CHECK-UNROLL: [[IV0:%[a-z.0-9]+]] = phi i32 [ 0, %entry ], [ [[IV16:%[a-z.0-9]+]], %for.body ]
+; CHECK-UNROLL: [[IV1:%[a-z.0-9]+]] = add nuw nsw i32 [[IV0]], 1
+; CHECK-UNROLL: [[IV2:%[a-z.0-9]+]] = add nuw nsw i32 [[IV1]], 1
+; CHECK-UNROLL: [[IV3:%[a-z.0-9]+]] = add nuw nsw i32 [[IV2]], 1
+; CHECK-UNROLL: [[IV4:%[a-z.0-9]+]] = add nuw nsw i32 [[IV3]], 1
+; CHECK-UNROLL: [[IV5:%[a-z.0-9]+]] = add nuw nsw i32 [[IV4]], 1
+; CHECK-UNROLL: [[IV6:%[a-z.0-9]+]] = add nuw nsw i32 [[IV5]], 1
+; CHECK-UNROLL: [[IV7:%[a-z.0-9]+]] = add nuw nsw i32 [[IV6]], 1
+; CHECK-UNROLL: [[IV8:%[a-z.0-9]+]] = add nuw nsw i32 [[IV7]], 1
+; CHECK-UNROLL: [[IV9:%[a-z.0-9]+]] = add nuw nsw i32 [[IV8]], 1
+; CHECK-UNROLL: [[IV10:%[a-z.0-9]+]] = add nuw nsw i32 [[IV9]], 1
+; CHECK-UNROLL: [[IV11:%[a-z.0-9]+]] = add nuw nsw i32 [[IV10]], 1
+; CHECK-UNROLL: [[IV12:%[a-z.0-9]+]] = add nuw nsw i32 [[IV11]], 1
+; CHECK-UNROLL: [[IV13:%[a-z.0-9]+]] = add nuw nsw i32 [[IV12]], 1
+; CHECK-UNROLL: [[IV14:%[a-z.0-9]+]] = add nuw nsw i32 [[IV13]], 1
+; CHECK-UNROLL: [[IV15:%[a-z.0-9]+]] = add nuw nsw i32 [[IV14]], 1
+; CHECK-UNROLL: [[IV16]] = add nuw nsw i32 [[IV15]], 1
+; CHECK-UNROLL: [[CMP:%[a-z.0-9]+]] = icmp eq i32 [[IV16]], 1024
+; CHECK-UNROLL: br i1 [[CMP]], label [[END:%[a-z.]+]], label %for.body
+
+  %i.08 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+  %arrayidx = getelementptr inbounds i32, i32* %A, i32 %i.08
+  %0 = load i32, i32* %arrayidx, align 4
+  %arrayidx1 = getelementptr inbounds i32, i32* %B, i32 %i.08
+  %1 = load i32, i32* %arrayidx1, align 4
+  %mul = mul nsw i32 %1, %0
+  %arrayidx2 = getelementptr inbounds i32, i32* %C, i32 %i.08
+  store i32 %mul, i32* %arrayidx2, align 4
+  %inc = add nuw nsw i32 %i.08, 1
+  %exitcond = icmp eq i32 %inc, 1024
+  br i1 %exitcond, label %for.cond.cleanup, label %for.body
+
+for.cond.cleanup:
+  ret void
+}
+
+; CHECK-LABEL: runtime
+define arm_aapcs_vfpcc void @runtime(i32* nocapture %C, i32* nocapture readonly %A, i32* nocapture readonly %B, i32 %N) local_unnamed_addr #0 {
+entry:
+  %cmp8 = icmp eq i32 %N, 0
+  br i1 %cmp8, label %for.cond.cleanup, label %for.body
+
+; CHECK-LABEL: for.body
+for.body:
+; CHECK-UNROLL-V7: [[IV0:%[a-z.0-9]+]] = phi i32 [ 0, [[PRE:%[a-z.0-9]+]] ], [ [[IV8:%[a-z.0-9]+]], %for.body ]
+; CHECK-UNROLL-V7: [[IV1:%[a-z.0-9]+]] = add nuw nsw i32 [[IV0]], 1
+; CHECK-UNROLL-V7: [[IV2]] = add nuw  i32 [[IV1]], 1
+
+; CHECK-UNROLL-SMALL: [[IV0:%[a-z.0-9]+]] = phi i32 [ 0, [[PRE:%[a-z.0-9]+]] ], [ [[IV8:%[a-z.0-9]+]], %for.body ]
+; CHECK-UNROLL-SMALL: [[IV1:%[a-z.0-9]+]] = add nuw nsw i32 [[IV0]], 1
+; CHECK-UNROLL-SMALL: [[IV2:%[a-z.0-9]+]] = add nuw nsw i32 [[IV1]], 1
+; CHECK-UNROLL-SMALL: [[IV3:%[a-z.0-9]+]] = add nuw nsw i32 [[IV2]], 1
+; CHECK-UNROLL-SMALL: [[IV4:%[a-z.0-9]+]] = add nuw nsw i32 [[IV3]], 1
+; CHECK-UNROLL-SMALL: [[IV5:%[a-z.0-9]+]] = add nuw nsw i32 [[IV4]], 1
+; CHECK-UNROLL-SMALL: [[IV6:%[a-z.0-9]+]] = add nuw nsw i32 [[IV5]], 1
+; CHECK-UNROLL-SMALL: [[IV7:%[a-z.0-9]+]] = add nuw nsw i32 [[IV6]], 1
+; CHECK-UNROLL-SMALL: [[IV8]] = add nuw i32 [[IV7]], 1
+
+; CHECK-UNROLL: [[IV0:%[a-z.0-9]+]] = phi i32 [ 0, [[PRE:%[a-z.0-9]+]] ], [ [[IV8:%[a-z.0-9]+]], %for.body ]
+; CHECK-UNROLL: [[IV1:%[a-z.0-9]+]] = add nuw nsw i32 [[IV0]], 1
+; CHECK-UNROLL: [[IV2:%[a-z.0-9]+]] = add nuw nsw i32 [[IV1]], 1
+; CHECK-UNROLL: [[IV3:%[a-z.0-9]+]] = add nuw nsw i32 [[IV2]], 1
+; CHECK-UNROLL: [[IV4:%[a-z.0-9]+]] = add nuw nsw i32 [[IV3]], 1
+; CHECK-UNROLL: [[IV5:%[a-z.0-9]+]] = add nuw nsw i32 [[IV4]], 1
+; CHECK-UNROLL: [[IV6:%[a-z.0-9]+]] = add nuw nsw i32 [[IV5]], 1
+; CHECK-UNROLL: [[IV7:%[a-z.0-9]+]] = add nuw nsw i32 [[IV6]], 1
+; CHECK-UNROLL: [[IV8]] = add nuw i32 [[IV7]], 1
+
+  %i.09 = phi i32 [ %inc, %for.body ], [ 0, %entry ]
+  %arrayidx = getelementptr inbounds i32, i32* %A, i32 %i.09
+  %0 = load i32, i32* %arrayidx, align 4
+  %arrayidx1 = getelementptr inbounds i32, i32* %B, i32 %i.09
+  %1 = load i32, i32* %arrayidx1, align 4
+  %mul = mul nsw i32 %1, %0
+  %arrayidx2 = getelementptr inbounds i32, i32* %C, i32 %i.09
+  store i32 %mul, i32* %arrayidx2, align 4
+  %inc = add nuw i32 %i.09, 1
+  %exitcond = icmp eq i32 %inc, %N
+  br i1 %exitcond, label %for.cond.cleanup, label %for.body
+
+for.cond.cleanup:
+  ret void
+}
+
+; CHECK-LABEL: nested_runtime
+define arm_aapcs_vfpcc void @nested_runtime(i32* nocapture %C, i16* nocapture readonly %A, i16* nocapture readonly %B, i32 %N) local_unnamed_addr #0 {
+entry:
+  %cmp25 = icmp eq i32 %N, 0
+  br i1 %cmp25, label %for.cond.cleanup, label %for.body4.lr.ph
+
+for.body4.lr.ph:
+  %h.026 = phi i32 [ %inc11, %for.cond.cleanup3 ], [ 0, %entry ]
+  %mul = mul i32 %h.026, %N
+  br label %for.body4
+
+for.cond.cleanup:
+  ret void
+
+for.cond.cleanup3:
+  %inc11 = add nuw i32 %h.026, 1
+  %exitcond27 = icmp eq i32 %inc11, %N
+  br i1 %exitcond27, label %for.cond.cleanup, label %for.body4.lr.ph
+
+; CHECK-LABEL: for.body4
+for.body4:
+; CHECK-UNROLL-V7: [[IV0:%[a-z.0-9]+]] = phi i32 [ 0, [[PRE:%[a-z0-9.]+]] ], [ [[IV1:%[a-z.0-9]+]], %for.body4 ]
+; CHECK-UNROLL-V7: [[IV1:%[a-z.0-9]+]] = add nuw  i32 [[IV0]], 1
+
+; CHECK-UNROLL-SMALL: [[IV0:%[a-z.0-9]+]] = phi i32 [ 0, [[PRE:%[a-z0-9.]+]] ], [ [[IV4:%[a-z.0-9]+]], %for.body4 ]
+; CHECK-UNROLL-SMALL: [[IV1:%[a-z.0-9]+]] = add nuw nsw i32 [[IV0]], 1
+; CHECK-UNROLL-SMALL: [[IV2:%[a-z.0-9]+]] = add nuw nsw i32 [[IV1]], 1
+; CHECK-UNROLL-SMALL: [[IV3:%[a-z.0-9]+]] = add nuw nsw i32 [[IV2]], 1
+; CHECK-UNROLL-SMALL: [[IV4]] = add nuw i32 [[IV3]], 1
+
+; CHECK-UNROLL: [[IV0:%[a-z.0-9]+]] = phi i32 [ 0, [[PRE:%[a-z0-9.]+]] ], [ [[IV8:%[a-z.0-9]+]], %for.body4 ]
+; CHECK-UNROLL: [[IV1:%[a-z.0-9]+]] = add nuw nsw i32 [[IV0]], 1
+; CHECK-UNROLL: [[IV2:%[a-z.0-9]+]] = add nuw nsw i32 [[IV1]], 1
+; CHECK-UNROLL: [[IV3:%[a-z.0-9]+]] = add nuw nsw i32 [[IV2]], 1
+; CHECK-UNROLL: [[IV4:%[a-z.0-9]+]] = add nuw nsw i32 [[IV3]], 1
+; CHECK-UNROLL: [[IV5:%[a-z.0-9]+]] = add nuw nsw i32 [[IV4]], 1
+; CHECK-UNROLL: [[IV6:%[a-z.0-9]+]] = add nuw nsw i32 [[IV5]], 1
+; CHECK-UNROLL: [[IV7:%[a-z.0-9]+]] = add nuw nsw i32 [[IV6]], 1
+; CHECK-UNROLL: [[IV8:%[a-z.0-9]+]] = add nuw i32 [[IV7]], 1
+
+  %w.024 = phi i32 [ 0, %for.body4.lr.ph ], [ %inc, %for.body4 ]
+  %add = add i32 %w.024, %mul
+  %arrayidx = getelementptr inbounds i16, i16* %A, i32 %add
+  %0 = load i16, i16* %arrayidx, align 2
+  %conv = sext i16 %0 to i32
+  %arrayidx5 = getelementptr inbounds i16, i16* %B, i32 %w.024
+  %1 = load i16, i16* %arrayidx5, align 2
+  %conv6 = sext i16 %1 to i32
+  %mul7 = mul nsw i32 %conv6, %conv
+  %arrayidx8 = getelementptr inbounds i32, i32* %C, i32 %w.024
+  %2 = load i32, i32* %arrayidx8, align 4
+  %add9 = add nsw i32 %mul7, %2
+  store i32 %add9, i32* %arrayidx8, align 4
+  %inc = add nuw i32 %w.024, 1
+  %exitcond = icmp eq i32 %inc, %N
+  br i1 %exitcond, label %for.cond.cleanup3, label %for.body4
+}
+
+; CHECK-LABEL: loop_call
+define arm_aapcs_vfpcc void @loop_call(i32* nocapture %C, i32* nocapture readonly %A, i32* nocapture readonly %B) local_unnamed_addr #1 {
+entry:
+  br label %for.body
+
+for.cond.cleanup:
+  ret void
+
+; CHECK-LABEL: for.body
+for.body:
+; CHECK-UNROLL-V7: [[IV0:%[a-z.0-9]+]] = phi i32 [ 0, %entry ], [ [[IV1:%[a-z.0-9]+]], %for.body ]
+; CHECK-UNROLL-V7: [[IV1]] = add nuw nsw i32 [[IV0]], 1
+; CHECK-UNROLL-V7: icmp eq i32 [[IV1]], 1024
+
+; CHECK-UNROLL-SMALL: [[IV0:%[a-z.0-9]+]] = phi i32 [ 0, %entry ], [ [[IV1:%[a-z.0-9]+]], %for.body ]
+; CHECK-UNROLL-SMALL: [[IV1]] = add nuw nsw i32 [[IV0]], 1
+; CHECK-UNROLL-SMALL: icmp eq i32 [[IV1]], 1024
+
+; CHECK-UNROLL: [[IV0:%[a-z.0-9]+]] = phi i32 [ 0, %entry ], [ [[IV1:%[a-z.0-9]+]], %for.body ]
+; CHECK-UNROLL: [[IV1]] = add nuw nsw i32 [[IV0]], 1
+; CHECK-UNROLL: icmp eq i32 [[IV1]], 1024
+
+  %i.08 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+  %arrayidx = getelementptr inbounds i32, i32* %A, i32 %i.08
+  %0 = load i32, i32* %arrayidx, align 4
+  %arrayidx1 = getelementptr inbounds i32, i32* %B, i32 %i.08
+  %1 = load i32, i32* %arrayidx1, align 4
+  %call = tail call arm_aapcs_vfpcc i32 @some_func(i32 %0, i32 %1) #3
+  %arrayidx2 = getelementptr inbounds i32, i32* %C, i32 %i.08
+  store i32 %call, i32* %arrayidx2, align 4
+  %inc = add nuw nsw i32 %i.08, 1
+  %exitcond = icmp eq i32 %inc, 1024
+  br i1 %exitcond, label %for.cond.cleanup, label %for.body
+}
+
+declare arm_aapcs_vfpcc i32 @some_func(i32, i32) local_unnamed_addr #2