[CodeGen] Generate follow-up metadata for loops with more than one transformation.

Before this patch, CGLoop would dump all transformations for a loop into
a single LoopID without encoding any order in which to apply them.
rL348944 added the possibility to encode a transformation order using
followup-attributes.

When a loop has more than one transformation, use the follow-up
attribute define the order in which they are applied. The emitted order
is the defacto order as defined by the current LLVM pass pipeline,
which is:

  LoopFullUnrollPass
  LoopDistributePass
  LoopVectorizePass
  LoopUnrollAndJamPass
  LoopUnrollPass
  MachinePipeliner

This patch should therefore not change the assembly output, assuming
that all explicit transformations can be applied, and no implicit
transformations in-between. In the former case,
WarnMissedTransformationsPass should emit a warning (except for
MachinePipeliner which is not implemented yet). The latter could be
avoided by adding 'llvm.loop.disable_nonforced' attributes.

Because LoopUnrollAndJamPass processes a loop nest, generation of the
MDNode is delayed to after the inner loop metadata have been processed.
A temporary LoopID is therefore used to annotate instructions and
RAUW'ed by the actual LoopID later.

Differential Revision: https://reviews.llvm.org/D57978

llvm-svn: 357415

1 files changed, 42 insertions, 0 deletions

diff --git a/clang/test/CodeGenCXX/pragma-followup_inner.cpp b/clang/test/CodeGenCXX/pragma-followup_inner.cpp
new file mode 100644
index 00000000000..62e9f07f019
--- /dev/null
+++ b/clang/test/CodeGenCXX/pragma-followup_inner.cpp
@@ -0,0 +1,42 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin -std=c++11 -emit-llvm -o - %s | FileCheck %s
+
+extern "C" void followup_inner(int n, int *x) {
+#pragma unroll_and_jam(4)
+  for(int j = 0; j < n; j++) {
+#pragma clang loop pipeline_initiation_interval(10)
+#pragma clang loop unroll_count(4)
+#pragma clang loop vectorize(assume_safety)
+#pragma clang loop distribute(enable)
+    for(int i = 0; i < n; i++)
+      x[j+i*n] = 10;
+
+  }
+}
+
+
+// CHECK-LABEL: define void @followup_inner
+// CHECK: br label %for.cond1, !llvm.loop ![[INNERLOOP_3:[0-9]+]]
+// CHECK: br label %for.cond, !llvm.loop ![[OUTERLOOP_9:[0-9]+]]
+
+// CHECK-DAG: ![[ACCESSGROUP_2:[0-9]+]] = distinct !{}
+
+// CHECK-DAG: ![[INNERLOOP_3:[0-9]+]] = distinct !{![[INNERLOOP_3:[0-9]+]], ![[PARALLEL_ACCESSES_4:[0-9]+]], ![[DISTRIBUTE_5:[0-9]+]], ![[DISTRIBUTE_FOLLOWUP_6:[0-9]+]]}
+// CHECK-DAG: ![[PARALLEL_ACCESSES_4:[0-9]+]] = !{!"llvm.loop.parallel_accesses", !2}
+// CHECK-DAG: ![[DISTRIBUTE_5:[0-9]+]] = !{!"llvm.loop.distribute.enable", i1 true}
+// CHECK-DAG: ![[DISTRIBUTE_FOLLOWUP_6:[0-9]+]] = !{!"llvm.loop.distribute.followup_all", ![[LOOP_7:[0-9]+]]}
+
+// CHECK-DAG: ![[LOOP_7:[0-9]+]] = distinct !{![[LOOP_7:[0-9]+]], ![[PARALLEL_ACCESSES_4:[0-9]+]], ![[VECTORIZE_8:[0-9]+]]}
+// CHECK-DAG: ![[VECTORIZE_8:[0-9]+]] = !{!"llvm.loop.vectorize.enable", i1 true}
+
+// CHECK-DAG: ![[OUTERLOOP_9:[0-9]+]] = distinct !{![[OUTERLOOP_9:[0-9]+]], ![[UNROLLANDJAM_COUNT_10:[0-9]+]], ![[UNROLLANDJAM_FOLLOWUPINNER_11:[0-9]+]]}
+// CHECK-DAG: ![[UNROLLANDJAM_COUNT_10:[0-9]+]] = !{!"llvm.loop.unroll_and_jam.count", i32 4}
+// CHECK-DAG: ![[UNROLLANDJAM_FOLLOWUPINNER_11:[0-9]+]] = !{!"llvm.loop.unroll_and_jam.followup_inner", !12}
+
+// CHECK-DAG: ![[LOOP_12:[0-9]+]] = distinct !{![[LOOP_12:[0-9]+]], ![[PARALLEL_ACCESSES_4:[0-9]+]], ![[ISVECTORIZED_13:[0-9]+]], ![[UNROLL_COUNT_13:[0-9]+]], ![[UNROLL_FOLLOWUP_14:[0-9]+]]}
+// CHECK-DAG: ![[ISVECTORIZED_13:[0-9]+]] = !{!"llvm.loop.isvectorized"}
+// CHECK-DAG: ![[UNROLL_COUNT_13:[0-9]+]] = !{!"llvm.loop.unroll.count", i32 4}
+// CHECK-DAG: ![[UNROLL_FOLLOWUP_14:[0-9]+]] = !{!"llvm.loop.unroll.followup_all", ![[LOOP_15:[0-9]+]]}
+
+// CHECK-DAG: ![[LOOP_15:[0-9]+]] = distinct !{![[LOOP_15:[0-9]+]], ![[PARALLEL_ACCESSES_4:[0-9]+]], ![[ISVECTORIZED_13:[0-9]+]], ![[UNROLL_DISABLE_16:[0-9]+]], ![[PIPELINE_17:[0-9]+]]}
+// CHECK-DAG: ![[UNROLL_DISABLE_16:[0-9]+]] = !{!"llvm.loop.unroll.disable"}
+// CHECK-DAG: ![[PIPELINE_17:[0-9]+]] = !{!"llvm.loop.pipeline.initiationinterval", i32 10}