[polly] r250958 - [FIX] Do not hoist nested variant base pointers

[Johannes Doerfert via llvm-commits]

Author: jdoerfert
Date: Wed Oct 21 17:14:57 2015
New Revision: 250958

URL: http://llvm.org/viewvc/llvm-project?rev=250958&view=rev
Log:
[FIX] Do not hoist nested variant base pointers

  This fixes bug 25249.


Added:
    polly/trunk/test/ScopInfo/variant_base_pointer.ll
Modified:
    polly/trunk/lib/Analysis/ScopInfo.cpp

Modified: polly/trunk/lib/Analysis/ScopInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/Analysis/ScopInfo.cpp?rev=250958&r1=250957&r2=250958&view=diff
==============================================================================
--- polly/trunk/lib/Analysis/ScopInfo.cpp (original)
+++ polly/trunk/lib/Analysis/ScopInfo.cpp Wed Oct 21 17:14:57 2015
@@ -2549,14 +2549,18 @@ void Scop::hoistInvariantLoads() {
       // not loaded inside the SCoP. This can happened e.g., if a readnone call
       // returns a pointer that is used as a base address. However, as we want
       // to hoist indirect pointers, we allow the base pointer to be defined in
-      // the region if it is also a memory access. Hence, if the ScopArrayInfo
-      // object has a base pointer origin we know the base pointer is loaded and
-      // that it is invariant, thus it will be hoisted too.
+      // the region if it is also a memory access. Each ScopArrayInfo object
+      // that has a base pointer origin has a base pointer that is loaded and
+      // that it is invariant, thus it will be hoisted too. However, if there is
+      // no bease pointer origin we check that the base pointer is defined
+      // outside the region.
       const ScopArrayInfo *SAI = MA->getScopArrayInfo();
-      if (!SAI->getBasePtrOriginSAI())
-        if (auto *BasePtrInst = dyn_cast<Instruction>(SAI->getBasePtr()))
-          if (R.contains(BasePtrInst))
-            continue;
+      while (auto *BasePtrOriginSAI = SAI->getBasePtrOriginSAI())
+        SAI = BasePtrOriginSAI;
+
+      if (auto *BasePtrInst = dyn_cast<Instruction>(SAI->getBasePtr()))
+        if (R.contains(BasePtrInst))
+          continue;
 
       // Skip accesses in non-affine subregions as they might not be executed
       // under the same condition as the entry of the non-affine subregion.

Added: polly/trunk/test/ScopInfo/variant_base_pointer.ll
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/test/ScopInfo/variant_base_pointer.ll?rev=250958&view=auto
==============================================================================
--- polly/trunk/test/ScopInfo/variant_base_pointer.ll (added)
+++ polly/trunk/test/ScopInfo/variant_base_pointer.ll Wed Oct 21 17:14:57 2015
@@ -0,0 +1,34 @@
+; RUN: opt %loadPolly -polly-ignore-aliasing -polly-scops -analyze < %s | FileCheck %s
+; RUN: opt %loadPolly -polly-ignore-aliasing -polly-codegen -analyze < %s
+;
+; CHECK:       Invariant Accesses: {
+; CHECK-NEXT:  }
+;
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+; Function Attrs: nounwind uwtable
+define void @cli_hex2int() {
+entry:
+  br label %if.end
+
+if.end:                                           ; preds = %entry
+  %call = call i16** @__ctype_b_loc() #0
+  %tmp = load i16*, i16** %call, align 8
+  %arrayidx = getelementptr inbounds i16, i16* %tmp, i64 0
+  %tmp1 = load i16, i16* %arrayidx, align 2
+  br i1 false, label %if.then.2, label %if.end.3
+
+if.then.2:                                        ; preds = %if.end
+  br label %cleanup
+
+if.end.3:                                         ; preds = %if.end
+  br label %cleanup
+
+cleanup:                                          ; preds = %if.end.3, %if.then.2
+  ret void
+}
+
+; Function Attrs: nounwind readnone
+declare i16** @__ctype_b_loc() #0
+
+attributes #0 = { nounwind readnone }