[llvm] r268177 - [SCEV] When printing via -analysis, dump loop disposition

[Sanjoy Das via llvm-commits]

Author: sanjoy
Date: Sat Apr 30 23:51:05 2016
New Revision: 268177

URL: http://llvm.org/viewvc/llvm-project?rev=268177&view=rev
Log:
[SCEV] When printing via -analysis, dump loop disposition

There are currently some bugs in tree around SCEV caching an incorrect
loop disposition.  Printing out loop dispositions will let us write
whitebox tests as those are fixed.

The dispositions are printed as a list in "inside out" order,
i.e. innermost loop first.

Added:
    llvm/trunk/test/Analysis/ScalarEvolution/scev-dispositions.ll
Modified:
    llvm/trunk/lib/Analysis/ScalarEvolution.cpp

Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=268177&r1=268176&r2=268177&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Sat Apr 30 23:51:05 2016
@@ -9565,6 +9565,17 @@ static void PrintLoopInfo(raw_ostream &O
   OS << "\n";
 }
 
+static StringRef loopDispositionToStr(ScalarEvolution::LoopDisposition LD) {
+  switch (LD) {
+  case ScalarEvolution::LoopVariant:
+    return "Variant";
+  case ScalarEvolution::LoopInvariant:
+    return "Invariant";
+  case ScalarEvolution::LoopComputable:
+    return "Computable";
+  }
+}
+
 void ScalarEvolution::print(raw_ostream &OS) const {
   // ScalarEvolution's implementation of the print method is to print
   // out SCEV values of all instructions that are interesting. Doing
@@ -9612,6 +9623,20 @@ void ScalarEvolution::print(raw_ostream
         } else {
           OS << *ExitValue;
         }
+
+        bool First = true;
+        for (auto *Iter = L; Iter; Iter = Iter->getParentLoop()) {
+          if (First) {
+            OS << "\t\t" "LoopDispositions: [ ";
+            First = false;
+          } else {
+            OS << ", ";
+          }
+
+          OS << loopDispositionToStr(SE.getLoopDisposition(SV, Iter));
+        }
+
+        OS << " ]";
       }
 
       OS << "\n";

Added: llvm/trunk/test/Analysis/ScalarEvolution/scev-dispositions.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/scev-dispositions.ll?rev=268177&view=auto
==============================================================================
--- llvm/trunk/test/Analysis/ScalarEvolution/scev-dispositions.ll (added)
+++ llvm/trunk/test/Analysis/ScalarEvolution/scev-dispositions.ll Sat Apr 30 23:51:05 2016
@@ -0,0 +1,73 @@
+; RUN: opt -analyze -scalar-evolution < %s | FileCheck %s
+
+define void @single_loop(i32* %buf, i32 %start) {
+; CHECK-LABEL: Classifying expressions for: @single_loop
+ entry:
+  %val = add i32 %start, 400
+  br label %loop
+
+ loop:
+  %counter = phi i32 [ 0, %entry ], [ %counter.inc, %loop ]
+  %idx = phi i32 [ %start, %entry ], [ %idx.inc, %loop ]
+
+; CHECK:  %counter = phi i32 [ 0, %entry ], [ %counter.inc, %loop ]
+; CHECK-NEXT:  -->  {{.*}} LoopDispositions: [ Computable ]
+; CHECK:  %idx = phi i32 [ %start, %entry ], [ %idx.inc, %loop ]
+; CHECK-NEXT:  -->  {{.*}} LoopDispositions: [ Computable ]
+; CHECK:  %val2 = add i32 %start, 400
+; CHECK-NEXT:  -->  {{.*}} LoopDispositions: [ Invariant ]
+; CHECK:  %idx.inc = add nsw i32 %idx, 1
+; CHECK-NEXT:  -->  {{.*}} LoopDispositions: [ Computable ]
+; CHECK:  %val3 = load volatile i32, i32* %buf
+; CHECK-NEXT:  -->  {{.*}} LoopDispositions: [ Variant ]
+
+  %val2 = add i32 %start, 400
+  %idx.inc = add nsw i32 %idx, 1
+  %idx.inc.sext = sext i32 %idx.inc to i64
+  %condition = icmp eq i32 %counter, 1
+  %counter.inc = add i32 %counter, 1
+  %val3 = load volatile i32, i32* %buf
+  br i1 %condition, label %exit, label %loop
+
+ exit:
+  ret void
+}
+
+
+define void @nested_loop(double* %p, i64 %m) {
+; CHECK-LABEL: Classifying expressions for: @nested_loop
+
+; CHECK:  %j = phi i64 [ 0, %entry ], [ %j.next, %outer.latch ]
+; CHECK-NEXT:  -->  {{.*}} LoopDispositions: [ Computable ]
+; CHECK:  %i = phi i64 [ 0, %outer.loop ], [ %i.next, %bb ]
+; CHECK-NEXT:  -->  {{.*}} LoopDispositions: [ Computable, Variant ]
+; CHECK:  %j.add = add i64 %j, 100
+; CHECK-NEXT:  -->  {{.*}} LoopDispositions: [ Invariant, Computable ]
+; CHECK:  %i.next = add i64 %i, 1
+; CHECK-NEXT:  -->  {{.*}} LoopDispositions: [ Computable, Variant ]
+; CHECK:  %j.next = add i64 %j, 91
+; CHECK-NEXT:  -->  {{.*}} LoopDispositions: [ Computable ]
+
+entry:
+  %k = icmp sgt i64 %m, 0
+  br i1 %k, label %outer.loop, label %return
+
+outer.loop:
+  %j = phi i64 [ 0, %entry ], [ %j.next, %outer.latch ]
+  br label %bb
+
+bb:
+  %i = phi i64 [ 0, %outer.loop ], [ %i.next, %bb ]
+  %j.add = add i64 %j, 100
+  %i.next = add i64 %i, 1
+  %exitcond = icmp eq i64 %i.next, 91
+  br i1 %exitcond, label %outer.latch, label %bb
+
+outer.latch:
+  %j.next = add i64 %j, 91
+  %h = icmp eq i64 %j.next, %m
+  br i1 %h, label %return, label %outer.loop
+
+return:
+  ret void
+}