[polly] r258105 - Make sure we preserve alignment information after hoisting invariant load

[Johannes Doerfert via llvm-commits]

Author: jdoerfert
Date: Mon Jan 18 18:17:21 2016
New Revision: 258105

URL: http://llvm.org/viewvc/llvm-project?rev=258105&view=rev
Log:
Make sure we preserve alignment information after hoisting invariant load

In Polly, after hoisting loop invariant loads outside loop, the alignment
information for hoisted loads are missing, this patch restore them.

Contributed-by: Lawrence Hu <lawrence at codeaurora.org>

Differential Revision: http://reviews.llvm.org/D16160


Added:
    polly/trunk/test/Isl/CodeGen/invaraint_load_hoist_alignment.ll
Modified:
    polly/trunk/include/polly/CodeGen/IslNodeBuilder.h
    polly/trunk/lib/CodeGen/IslNodeBuilder.cpp

Modified: polly/trunk/include/polly/CodeGen/IslNodeBuilder.h
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/include/polly/CodeGen/IslNodeBuilder.h?rev=258105&r1=258104&r2=258105&view=diff
==============================================================================
--- polly/trunk/include/polly/CodeGen/IslNodeBuilder.h (original)
+++ polly/trunk/include/polly/CodeGen/IslNodeBuilder.h Mon Jan 18 18:17:21 2016
@@ -215,7 +215,7 @@ protected:
   ///
   /// @returns The preloaded value casted to type @p Ty
   Value *preloadUnconditionally(__isl_take isl_set *AccessRange,
-                                isl_ast_build *Build, Type *Ty);
+                                isl_ast_build *Build, Instruction *AccInst);
 
   /// @brief Preload the memory load access @p MA.
   ///

Modified: polly/trunk/lib/CodeGen/IslNodeBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/lib/CodeGen/IslNodeBuilder.cpp?rev=258105&r1=258104&r2=258105&view=diff
==============================================================================
--- polly/trunk/lib/CodeGen/IslNodeBuilder.cpp (original)
+++ polly/trunk/lib/CodeGen/IslNodeBuilder.cpp Mon Jan 18 18:17:21 2016
@@ -893,15 +893,20 @@ bool IslNodeBuilder::materializeParamete
 }
 
 Value *IslNodeBuilder::preloadUnconditionally(isl_set *AccessRange,
-                                              isl_ast_build *Build, Type *Ty) {
+                                              isl_ast_build *Build,
+                                              Instruction *AccInst) {
   isl_pw_multi_aff *PWAccRel = isl_pw_multi_aff_from_set(AccessRange);
   PWAccRel = isl_pw_multi_aff_gist_params(PWAccRel, S.getContext());
   isl_ast_expr *Access =
       isl_ast_build_access_from_pw_multi_aff(Build, PWAccRel);
   Value *PreloadVal = ExprBuilder.create(Access);
 
+  if (LoadInst *PreloadInst = dyn_cast<LoadInst>(PreloadVal))
+    PreloadInst->setAlignment(dyn_cast<LoadInst>(AccInst)->getAlignment());
+
   // Correct the type as the SAI might have a different type than the user
   // expects, especially if the base pointer is a struct.
+  Type *Ty = AccInst->getType();
   if (Ty == PreloadVal->getType())
     return PreloadVal;
 
@@ -916,6 +921,9 @@ Value *IslNodeBuilder::preloadUnconditio
   Ptr = Builder.CreatePointerCast(Ptr, Ty->getPointerTo(),
                                   Ptr->getName() + ".cast");
   PreloadVal = Builder.CreateLoad(Ptr, LInst->getName());
+  if (LoadInst *PreloadInst = dyn_cast<LoadInst>(PreloadVal))
+    PreloadInst->setAlignment(dyn_cast<LoadInst>(AccInst)->getAlignment());
+
   LInst->eraseFromParent();
   return PreloadVal;
 }
@@ -940,7 +948,7 @@ Value *IslNodeBuilder::preloadInvariantL
 
   Value *PreloadVal = nullptr;
   if (AlwaysExecuted) {
-    PreloadVal = preloadUnconditionally(AccessRange, Build, AccInstTy);
+    PreloadVal = preloadUnconditionally(AccessRange, Build, AccInst);
     isl_ast_build_free(Build);
     isl_set_free(Domain);
     return PreloadVal;
@@ -984,8 +992,7 @@ Value *IslNodeBuilder::preloadInvariantL
   Builder.CreateBr(MergeBB);
 
   Builder.SetInsertPoint(ExecBB->getTerminator());
-  Value *PreAccInst = preloadUnconditionally(AccessRange, Build, AccInstTy);
-
+  Value *PreAccInst = preloadUnconditionally(AccessRange, Build, AccInst);
   Builder.SetInsertPoint(MergeBB->getTerminator());
   auto *MergePHI = Builder.CreatePHI(
       AccInstTy, 2, "polly.preload." + AccInst->getName() + ".merge");

Added: polly/trunk/test/Isl/CodeGen/invaraint_load_hoist_alignment.ll
URL: http://llvm.org/viewvc/llvm-project/polly/trunk/test/Isl/CodeGen/invaraint_load_hoist_alignment.ll?rev=258105&view=auto
==============================================================================
--- polly/trunk/test/Isl/CodeGen/invaraint_load_hoist_alignment.ll (added)
+++ polly/trunk/test/Isl/CodeGen/invaraint_load_hoist_alignment.ll Mon Jan 18 18:17:21 2016
@@ -0,0 +1,31 @@
+; RUN: opt %loadPolly -basicaa -polly-codegen -polly-vectorizer=polly -S %s | FileCheck %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-unknown-linux-gnu"
+
+ at A = common global [1024 x i32] zeroinitializer, align 16
+ at B = common global [1024 x i32] zeroinitializer, align 16
+
+declare i32 @foo(i32) readnone
+
+define void @force_alignment() nounwind {
+;CHECK: @force_alignment
+;CHECK-FORCED: @force_alignment
+entry:
+  br label %body
+
+body:
+  %indvar = phi i64 [ 0, %entry ], [ %indvar_next, %body ]
+  %scevgep = getelementptr [1024 x i32], [1024 x i32]* @B, i64 0, i64 %indvar
+; CHECK: [[T2:%.load]] = load i32, i32* getelementptr inbounds ([1024 x i32], [1024 x i32]* @A, i32 0, i32 0), align 4
+; CHECK: %value_p.splatinsert = insertelement <4 x i32> undef, i32 [[T2]], i32 0
+  %value = load i32, i32* getelementptr inbounds ([1024 x i32], [1024 x i32]* @A, i64 0, i64 0), align 4
+  %result = tail call i32 @foo(i32 %value) nounwind
+  store i32 %result, i32* %scevgep, align 4
+  %indvar_next = add i64 %indvar, 1
+  %exitcond = icmp eq i64 %indvar_next, 4
+  br i1 %exitcond, label %return, label %body
+
+return:
+  ret void
+}
+