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.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210721 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 285 insertions, 0 deletions

diff --git a/test/Transforms/LoopUnroll/unroll-pragmas.ll b/test/Transforms/LoopUnroll/unroll-pragmas.ll
new file mode 100644
index 0000000000..c8032f771d
--- /dev/null
+++ b/test/Transforms/LoopUnroll/unroll-pragmas.ll
@@ -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}