[LoopDataPrefetch] Add optimization remark

With -Rpass=loop-data-prefetch, show the memory access that got
prefetched.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@268578 91177308-0d34-0410-b5e6-96231b3b80d8

Author: anemet

lib/Transforms/Scalar/LoopDataPrefetch.cpp

@@ -26,6 +26,7 @@
 #include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/Analysis/ValueTracking.h"
 #include "llvm/IR/CFG.h"
+#include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/Dominators.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/IntrinsicInst.h"
@@ -209,9 +210,10 @@ bool LoopDataPrefetch::runOnLoop(Loop *L) {
   if (ItersAhead > getMaxPrefetchIterationsAhead())
     return MadeChange;
 
+  Function *F = L->getHeader()->getParent();
   DEBUG(dbgs() << "Prefetching " << ItersAhead
                << " iterations ahead (loop size: " << LoopSize << ") in "
-               << L->getHeader()->getParent()->getName() << ": " << *L);
+               << F->getName() << ": " << *L);
 
   SmallVector<std::pair<Instruction *, const SCEVAddRecExpr *>, 16> PrefLoads;
   for (Loop::block_iterator I = L->block_begin(), IE = L->block_end();
@@ -291,6 +293,9 @@ bool LoopDataPrefetch::runOnLoop(Loop *L) {
       ++NumPrefetches;
       DEBUG(dbgs() << "  Access: " << *PtrValue << ", SCEV: " << *LSCEV
                    << "\n");
+      emitOptimizationRemark(F->getContext(), DEBUG_TYPE, *F,
+                             MemI->getDebugLoc(), "prefetched memory access");
+
 
       MadeChange = true;
     }

test/Transforms/LoopDataPrefetch/AArch64/opt-remark.ll

@@ -0,0 +1,78 @@
+; RUN: opt -mcpu=cyclone -mtriple=arm64-apple-ios -loop-data-prefetch \
+; RUN:     -pass-remarks=loop-data-prefetch -S -max-prefetch-iters-ahead=100 \
+; RUN:     < %s 2>&1 | FileCheck %s
+
+; ModuleID = '/tmp/s.c'
+source_filename = "/tmp/s.c"
+target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
+target triple = "arm64-apple-ios5.0.0"
+
+;   1	struct MyStruct {
+;   2	  int field;
+;   3	  char kk[2044];
+;   4	} *my_struct;
+;   5
+;   6	int f(struct MyStruct *p, int N) {
+;   7	  int total = 0;
+;   8	  for (int i = 0; i < N; i++) {
+;   9	    total += my_struct[i].field;
+;  10	  }
+;  11	  return total;
+;  12	}
+
+; CHECK: remark: /tmp/s.c:9:27: prefetched memory access
+
+%struct.MyStruct = type { i32, [2044 x i8] }
+
+@my_struct = common global %struct.MyStruct* null, align 8
+
+define i32 @f(%struct.MyStruct* nocapture readnone %p, i32 %N) !dbg !6 {
+entry:
+  %cmp6 = icmp sgt i32 %N, 0, !dbg !8
+  br i1 %cmp6, label %for.body.lr.ph, label %for.cond.cleanup, !dbg !9
+
+for.body.lr.ph:                                   ; preds = %entry
+  %0 = load %struct.MyStruct*, %struct.MyStruct** @my_struct, align 8, !dbg !10, !tbaa !11
+  br label %for.body, !dbg !9
+
+for.cond.cleanup:                                 ; preds = %for.body, %entry
+  %total.0.lcssa = phi i32 [ 0, %entry ], [ %add, %for.body ]
+  ret i32 %total.0.lcssa, !dbg !15
+
+for.body:                                         ; preds = %for.body, %for.body.lr.ph
+  %indvars.iv = phi i64 [ 0, %for.body.lr.ph ], [ %indvars.iv.next, %for.body ]
+  %total.07 = phi i32 [ 0, %for.body.lr.ph ], [ %add, %for.body ]
+  %field = getelementptr inbounds %struct.MyStruct, %struct.MyStruct* %0, i64 %indvars.iv, i32 0, !dbg !16
+  %1 = load i32, i32* %field, align 4, !dbg !16, !tbaa !17
+  %add = add nsw i32 %1, %total.07, !dbg !20
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1, !dbg !9
+  %lftr.wideiv = trunc i64 %indvars.iv.next to i32, !dbg !9
+  %exitcond = icmp eq i32 %lftr.wideiv, %N, !dbg !9
+  br i1 %exitcond, label %for.cond.cleanup, label %for.body, !dbg !9
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+!llvm.ident = !{!5}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.9.0", isOptimized: true, runtimeVersion: 0, emissionKind: NoDebug, enums: !2)
+!1 = !DIFile(filename: "/tmp/s.c", directory: "/tmp")
+!2 = !{}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{i32 1, !"PIC Level", i32 2}
+!5 = !{!"clang version 3.9.0"}
+!6 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 6, type: !7, isLocal: false, isDefinition: true, scopeLine: 6, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !2)
+!7 = !DISubroutineType(types: !2)
+!8 = !DILocation(line: 8, column: 21, scope: !6)
+!9 = !DILocation(line: 8, column: 3, scope: !6)
+!10 = !DILocation(line: 9, column: 14, scope: !6)
+!11 = !{!12, !12, i64 0}
+!12 = !{!"any pointer", !13, i64 0}
+!13 = !{!"omnipotent char", !14, i64 0}
+!14 = !{!"Simple C/C++ TBAA"}
+!15 = !DILocation(line: 11, column: 3, scope: !6)
+!16 = !DILocation(line: 9, column: 27, scope: !6)
+!17 = !{!18, !19, i64 0}
+!18 = !{!"MyStruct", !19, i64 0, !13, i64 4}
+!19 = !{!"int", !13, i64 0}
+!20 = !DILocation(line: 9, column: 11, scope: !6)