[polly] r278792 - [ScopInfo] Make scalars used by PHIs in non-affine regions available

[Tobias Grosser via llvm-commits]

Author: grosser
Date: Tue Aug 16 06:44:48 2016
New Revision: 278792

URL: http://llvm.org/viewvc/llvm-project?rev=278792&view=rev
Log:
[ScopInfo] Make scalars used by PHIs in non-affine regions available

Normally this is ensured when adding PHI nodes, but as PHI node dependences
do not need to be added in case all incoming blocks are within the same
non-affine region, this was missed.

This corrects an issue visible in LNT's sqlite3, in case invariant load hoisting
was disabled.

Added:
    polly/trunk/test/ScopInfo/phi-in-non-affine-region.ll
Modified:
    polly/trunk/lib/Analysis/ScopBuilder.cpp

Modified: polly/trunk/lib/Analysis/ScopBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Analysis/ScopBuilder.cpp?rev=278792&r1=278791&r2=278792&view=diff
==============================================================================
--- polly/trunk/lib/Analysis/ScopBuilder.cpp (original)
+++ polly/trunk/lib/Analysis/ScopBuilder.cpp Tue Aug 16 06:44:48 2016
@@ -68,9 +68,14 @@ void ScopBuilder::buildPHIAccesses(PHINo
     Value *Op = PHI->getIncomingValue(u);
     BasicBlock *OpBB = PHI->getIncomingBlock(u);
 
-    // Do not build scalar dependences inside a non-affine subregion.
-    if (NonAffineSubRegion && NonAffineSubRegion->contains(OpBB))
+    // Do not build PHI dependences inside a non-affine subregion, but make
+    // sure that the necessary scalar values are still made available.
+    if (NonAffineSubRegion && NonAffineSubRegion->contains(OpBB)) {
+      auto *OpInst = dyn_cast<Instruction>(Op);
+      if (!OpInst || !NonAffineSubRegion->contains(OpInst))
+        ensureValueRead(Op, OpBB);
       continue;
+    }
 
     OnlyNonAffineSubRegionOperands = false;
     ensurePHIWrite(PHI, OpBB, Op, IsExitBlock);

Added: polly/trunk/test/ScopInfo/phi-in-non-affine-region.ll
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/test/ScopInfo/phi-in-non-affine-region.ll?rev=278792&view=auto
==============================================================================
--- polly/trunk/test/ScopInfo/phi-in-non-affine-region.ll (added)
+++ polly/trunk/test/ScopInfo/phi-in-non-affine-region.ll Tue Aug 16 06:44:48 2016
@@ -0,0 +1,61 @@
+; RUN: opt %loadPolly -analyze -polly-scops < %s | FileCheck %s
+
+; Verify that 'tmp' is stored in bb1 and read by bb3, as it is needed as
+; incoming value for the tmp11 PHI node.
+
+; CHECK: Stmt_bb1
+; CHECK-NEXT:   Domain :=
+; CHECK-NEXT:       { Stmt_bb1[] };
+; CHECK-NEXT:   Schedule :=
+; CHECK-NEXT:       { Stmt_bb1[] -> [0] };
+; CHECK-NEXT:   ReadAccess :=	[Reduction Type: NONE] [Scalar: 0]
+; CHECK-NEXT:       { Stmt_bb1[] -> MemRef_global[0] };
+; CHECK-NEXT:   MustWriteAccess :=	[Reduction Type: NONE] [Scalar: 1]
+; CHECK-NEXT:       { Stmt_bb1[] -> MemRef_tmp[] };
+; CHECK-NEXT: Stmt_bb3__TO__bb10
+; CHECK-NEXT:   Domain :=
+; CHECK-NEXT:       { Stmt_bb3__TO__bb10[] };
+; CHECK-NEXT:   Schedule :=
+; CHECK-NEXT:       { Stmt_bb3__TO__bb10[] -> [1] };
+; CHECK-NEXT:   ReadAccess :=	[Reduction Type: NONE] [Scalar: 1]
+; CHECK-NEXT:       { Stmt_bb3__TO__bb10[] -> MemRef_tmp[] };
+; CHECK-NEXT:   MustWriteAccess :=	[Reduction Type: NONE] [Scalar: 1]
+; CHECK-NEXT:       { Stmt_bb3__TO__bb10[] -> MemRef_tmp11[] };
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+%struct.hoge = type { double, double, i8, i8, i8 }
+
+ at global = external local_unnamed_addr global %struct.hoge, align 8
+
+define void @widget() local_unnamed_addr {
+bb:
+  br label %bb1
+
+bb1:                                              ; preds = %bb
+  %tmp = load double, double* getelementptr inbounds (%struct.hoge, %struct.hoge* @global, i64 0, i32 0), align 8
+  br i1 false, label %bb3, label %bb2
+
+bb2:                                              ; preds = %bb1
+  br label %bb3
+
+bb3:                                              ; preds = %bb2, %bb1
+  br i1 false, label %bb8, label %bb4
+
+bb4:                                              ; preds = %bb3
+  br label %bb5
+
+bb5:                                              ; preds = %bb4
+  %tmp6 = and i32 undef, 16711680
+  %tmp7 = icmp eq i32 %tmp6, 0
+  br i1 %tmp7, label %bb8, label %bb10
+
+bb8:                                              ; preds = %bb5, %bb3
+  %tmp9 = phi double [ %tmp, %bb3 ], [ undef, %bb5 ]
+  br label %bb10
+
+bb10:                                             ; preds = %bb8, %bb5
+  %tmp11 = phi double [ undef, %bb5 ], [ %tmp9, %bb8 ]
+  ret void
+}