[PATCH] D16160: Make sure we preserve alignment information after hoisting invariant load

[Lawrence Hu via llvm-commits]

hulx2000 updated this revision to Diff 44929.
hulx2000 added a comment.

updated to address Johannes's comment, thanks Johannes


Repository:
  rL LLVM

http://reviews.llvm.org/D16160

Files:
  include/polly/CodeGen/IslNodeBuilder.h
  lib/CodeGen/IslNodeBuilder.cpp
  test/Isl/CodeGen/invaraint_load_hoist_alignment.ll

Index: test/Isl/CodeGen/invaraint_load_hoist_alignment.ll
===================================================================
--- /dev/null
+++ test/Isl/CodeGen/invaraint_load_hoist_alignment.ll
@@ -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
+}
+
Index: lib/CodeGen/IslNodeBuilder.cpp
===================================================================
--- lib/CodeGen/IslNodeBuilder.cpp
+++ lib/CodeGen/IslNodeBuilder.cpp
@@ -893,15 +893,20 @@
 }
 
 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;
 
@@ -940,7 +945,7 @@
 
   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 +989,7 @@
   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");
Index: include/polly/CodeGen/IslNodeBuilder.h
===================================================================
--- include/polly/CodeGen/IslNodeBuilder.h
+++ include/polly/CodeGen/IslNodeBuilder.h
@@ -215,7 +215,7 @@
   ///
   /// @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.
   ///


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