[polly] r268222 - [ScheduleOptimizer] Add -polly-opt-outer-coincidence option.

[Michael Kruse via llvm-commits]

Author: meinersbur
Date: Mon May  2 06:35:27 2016
New Revision: 268222

URL: http://llvm.org/viewvc/llvm-project?rev=268222&view=rev
Log:
[ScheduleOptimizer] Add -polly-opt-outer-coincidence option.

Add a command line switch to set the
isl_options_set_schedule_outer_coincidence option. ISL then tries to
build schedules where the outer member of a band satisfies the
coincidence constraints.

In practice this allows loop skewing for more parallelism in inner
loops.

Added:
    polly/trunk/test/ScheduleOptimizer/outer_coincidence.ll
Modified:
    polly/trunk/lib/Transform/ScheduleOptimizer.cpp

Modified: polly/trunk/lib/Transform/ScheduleOptimizer.cpp
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Transform/ScheduleOptimizer.cpp?rev=268222&r1=268221&r2=268222&view=diff
==============================================================================
--- polly/trunk/lib/Transform/ScheduleOptimizer.cpp (original)
+++ polly/trunk/lib/Transform/ScheduleOptimizer.cpp Mon May  2 06:35:27 2016
@@ -102,6 +102,12 @@ static cl::opt<std::string>
                       cl::desc("Maximize the band depth (yes/no)"), cl::Hidden,
                       cl::init("yes"), cl::ZeroOrMore, cl::cat(PollyCategory));
 
+static cl::opt<std::string> OuterCoincidence(
+    "polly-opt-outer-coincidence",
+    cl::desc("Try to construct schedules where the outer member of each band "
+             "satisfies the coincidence constraints (yes/no)"),
+    cl::Hidden, cl::init("no"), cl::ZeroOrMore, cl::cat(PollyCategory));
+
 static cl::opt<int> PrevectorWidth(
     "polly-prevect-width",
     cl::desc(
@@ -543,6 +549,20 @@ bool IslScheduleOptimizer::runOnScop(Sco
     IslMaximizeBands = 1;
   }
 
+  int IslOuterCoincidence;
+
+  if (OuterCoincidence == "yes") {
+    IslOuterCoincidence = 1;
+  } else if (OuterCoincidence == "no") {
+    IslOuterCoincidence = 0;
+  } else {
+    errs() << "warning: Option -polly-opt-outer-coincidence should either be "
+              "'yes' or 'no'. Falling back to default: 'no'\n";
+    IslOuterCoincidence = 0;
+  }
+
+  isl_options_set_schedule_outer_coincidence(S.getIslCtx(),
+                                             IslOuterCoincidence);
   isl_options_set_schedule_serialize_sccs(S.getIslCtx(), IslSerializeSCCs);
   isl_options_set_schedule_maximize_band_depth(S.getIslCtx(), IslMaximizeBands);
   isl_options_set_schedule_max_constant_term(S.getIslCtx(), MaxConstantTerm);

Added: polly/trunk/test/ScheduleOptimizer/outer_coincidence.ll
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/test/ScheduleOptimizer/outer_coincidence.ll?rev=268222&view=auto
==============================================================================
--- polly/trunk/test/ScheduleOptimizer/outer_coincidence.ll (added)
+++ polly/trunk/test/ScheduleOptimizer/outer_coincidence.ll Mon May  2 06:35:27 2016
@@ -0,0 +1,69 @@
+; RUN: opt %loadPolly -polly-opt-isl -polly-ast -polly-tiling=0 -polly-parallel -polly-opt-outer-coincidence=no -analyze < %s | FileCheck %s
+; RUN: opt %loadPolly -polly-opt-isl -polly-ast -polly-tiling=0 -polly-parallel -polly-opt-outer-coincidence=yes -analyze < %s | FileCheck %s --check-prefix=OUTER
+
+; By skewing, the diagonal can be made parallel. ISL does this when the Check
+; the 'outer_coincidence' option is enabled.
+;
+; void func(int m, int n, float A[static const restrict m][n]) {
+;  for (int i = 1; i < m; i+=1)
+;    for (int j = 1; j < n; j+=1)
+;      A[i][j] = A[i-1][j] + A[i][j-1];
+;}
+
+define void @func(i64 %m, i64 %n, float* noalias nonnull %A) #0 {
+entry:
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.inc11, %entry
+  %i.0 = phi i64 [ 1, %entry ], [ %add12, %for.inc11 ]
+  %cmp = icmp slt i64 %i.0, %m
+  br i1 %cmp, label %for.cond1.preheader, label %for.end13
+
+for.cond1.preheader:                              ; preds = %for.cond
+  br label %for.cond1
+
+for.cond1:                                        ; preds = %for.cond1.preheader, %for.body3
+  %j.0 = phi i64 [ %add10, %for.body3 ], [ 1, %for.cond1.preheader ]
+  %cmp2 = icmp slt i64 %j.0, %n
+  br i1 %cmp2, label %for.body3, label %for.inc11
+
+for.body3:                                        ; preds = %for.cond1
+  %sub = add nsw i64 %i.0, -1
+  %tmp = mul nsw i64 %sub, %n
+  %arrayidx = getelementptr inbounds float, float* %A, i64 %tmp
+  %arrayidx4 = getelementptr inbounds float, float* %arrayidx, i64 %j.0
+  %tmp13 = load float, float* %arrayidx4, align 4
+  %sub5 = add nsw i64 %j.0, -1
+  %tmp14 = mul nsw i64 %i.0, %n
+  %arrayidx6 = getelementptr inbounds float, float* %A, i64 %tmp14
+  %arrayidx7 = getelementptr inbounds float, float* %arrayidx6, i64 %sub5
+  %tmp15 = load float, float* %arrayidx7, align 4
+  %add = fadd float %tmp13, %tmp15
+  %tmp16 = mul nsw i64 %i.0, %n
+  %arrayidx8 = getelementptr inbounds float, float* %A, i64 %tmp16
+  %arrayidx9 = getelementptr inbounds float, float* %arrayidx8, i64 %j.0
+  store float %add, float* %arrayidx9, align 4
+  %add10 = add nuw nsw i64 %j.0, 1
+  br label %for.cond1
+
+for.inc11:                                        ; preds = %for.cond1
+  %add12 = add nuw nsw i64 %i.0, 1
+  br label %for.cond
+
+for.end13:                                        ; preds = %for.cond
+  ret void
+}
+
+
+; CHECK:      #pragma minimal dependence distance: 1
+; CHECK-NEXT: for (int c0 = 0; c0 < m - 1; c0 += 1)
+; CHECK-NEXT:   #pragma minimal dependence distance: 1
+; CHECK-NEXT:   for (int c1 = 0; c1 < n - 1; c1 += 1)
+; CHECK-NEXT:     Stmt_for_body3(c0, c1);
+
+; OUTER:      #pragma minimal dependence distance: 1
+; OUTER-NEXT: for (int c0 = 0; c0 < m + n - 3; c0 += 1)
+; OUTER-NEXT:   #pragma simd
+; OUTER-NEXT:   #pragma known-parallel
+; OUTER-NEXT:   for (int c1 = max(0, -m + c0 + 2); c1 <= min(n - 2, c0); c1 += 1)
+; OUTER-NEXT:     Stmt_for_body3(c0 - c1, c1);