[polly] r270409 - [FIX] Let ScalarEvolution forget hoisted values

[Johannes Doerfert via llvm-commits]

Author: jdoerfert
Date: Mon May 23 04:02:54 2016
New Revision: 270409

URL: http://llvm.org/viewvc/llvm-project?rev=270409&view=rev
Log:
[FIX] Let ScalarEvolution forget hoisted values

  We have to rethink the handling of escaping values in order to make
  this kind of "fixes" go away.


Added:
    polly/trunk/test/Isl/CodeGen/hoisted_load_escapes_through_phi.ll
Modified:
    polly/trunk/lib/CodeGen/IslNodeBuilder.cpp

Modified: polly/trunk/lib/CodeGen/IslNodeBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/CodeGen/IslNodeBuilder.cpp?rev=270409&r1=270408&r2=270409&view=diff
==============================================================================
--- polly/trunk/lib/CodeGen/IslNodeBuilder.cpp (original)
+++ polly/trunk/lib/CodeGen/IslNodeBuilder.cpp Mon May 23 04:02:54 2016
@@ -960,6 +960,11 @@ Value *IslNodeBuilder::preloadUnconditio
   if (LoadInst *PreloadInst = dyn_cast<LoadInst>(PreloadVal))
     PreloadInst->setAlignment(dyn_cast<LoadInst>(AccInst)->getAlignment());
 
+  // TODO: This is only a hot fix for SCoP sequences that use the same load
+  //       instruction contained and hoisted by one of the SCoPs.
+  if (SE.isSCEVable(Ty))
+    SE.forgetValue(AccInst);
+
   return PreloadVal;
 }
 

Added: polly/trunk/test/Isl/CodeGen/hoisted_load_escapes_through_phi.ll
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/test/Isl/CodeGen/hoisted_load_escapes_through_phi.ll?rev=270409&view=auto
==============================================================================
--- polly/trunk/test/Isl/CodeGen/hoisted_load_escapes_through_phi.ll (added)
+++ polly/trunk/test/Isl/CodeGen/hoisted_load_escapes_through_phi.ll Mon May 23 04:02:54 2016
@@ -0,0 +1,59 @@
+; RUN: opt %loadPolly -S -polly-codegen < %s | FileCheck %s
+;
+; Check that we generate valid code even if the load of cont_STACKPOINTER is
+; hoisted in one SCoP and used (through the phi node %tmp2).
+;
+; CHECK: polly.start
+; CHECK: polly.start
+;
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+%struct1 = type { i32, %union1, %struct.2*, i32, i32 }
+%union1 = type { %struct.2* }
+%struct.2 = type { %struct.2*, i8* }
+
+ at cont_STACKPOINTER = external global i32, align 4
+ at cont_STACK = external global [1000 x i32], align 16
+
+define fastcc void @subs_InternIdcEq() {
+entry:
+  br label %if.else.i.i
+
+if.else.i.i:                                      ; preds = %entry
+  %tmp = load %struct1*, %struct1** undef, align 8
+  br label %while.body.i99.i.i
+
+while.body.i99.i.i:                               ; preds = %while.body.i99.i.i, %if.else.i.i
+  br i1 false, label %while.body.i99.i.i, label %while.end.i103.i.i
+
+while.end.i103.i.i:                               ; preds = %while.body.i99.i.i
+  %tmp1 = load i32, i32* @cont_STACKPOINTER, align 4
+  %dec.i.i102.i.i = add nsw i32 %tmp1, -1
+  br i1 false, label %cont_BackTrack.exit107.i.i, label %if.then.i106.i.i
+
+if.then.i106.i.i:                                 ; preds = %while.end.i103.i.i
+  br label %cont_BackTrack.exit107.i.i
+
+cont_BackTrack.exit107.i.i:                       ; preds = %if.then.i106.i.i, %while.end.i103.i.i
+  %tmp2 = phi i32 [ %dec.i.i102.i.i, %if.then.i106.i.i ], [ 0, %while.end.i103.i.i ]
+  %symbol.i.i.i = getelementptr inbounds %struct1, %struct1* %tmp, i64 0, i32 0
+  br i1 undef, label %land.lhs.true23.i.i, label %for.inc.i.i
+
+land.lhs.true23.i.i:                              ; preds = %cont_BackTrack.exit107.i.i
+  %idxprom.i.i57.i.i = sext i32 %tmp2 to i64
+  %arrayidx.i.i58.i.i = getelementptr inbounds [1000 x i32], [1000 x i32]* @cont_STACK, i64 0, i64 %idxprom.i.i57.i.i
+  store i32 undef, i32* %arrayidx.i.i58.i.i, align 4
+  br i1 false, label %if.then.i45.i.i, label %fol_Atom.exit47.i.i
+
+if.then.i45.i.i:                                  ; preds = %land.lhs.true23.i.i
+  br label %fol_Atom.exit47.i.i
+
+fol_Atom.exit47.i.i:                              ; preds = %if.then.i45.i.i, %land.lhs.true23.i.i
+  unreachable
+
+for.inc.i.i:                                      ; preds = %cont_BackTrack.exit107.i.i
+  br label %for.end.i.i
+
+for.end.i.i:                                      ; preds = %for.inc.i.i
+  ret void
+}