Revert 172027 and 174336. Remove diagnostics about over-aligned stack objects.

Aside from the question of whether we report a warning or an error when we
can't satisfy a requested stack object alignment, the current implementation
of this is not good.  We're not providing any source location in the diagnostics
and the current warning is not connected to any warning group so you can't
control it.  We could improve the source location somewhat, but we can do a
much better job if this check is implemented in the front-end, so let's do that
instead.  <rdar://problem/13127907>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174741 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 24 insertions, 70 deletions

diff --git a/include/llvm/CodeGen/MachineFrameInfo.h b/include/llvm/CodeGen/MachineFrameInfo.h
index 0748b9a..93d7728 100644
--- a/include/llvm/CodeGen/MachineFrameInfo.h
+++ b/include/llvm/CodeGen/MachineFrameInfo.h
@@ -493,23 +493,11 @@ public:
     return Objects[ObjectIdx+NumFixedObjects].Size == ~0ULL;
   }
 
-  /// CreateStackObjectWithMinAlign - Create a new statically sized stack
-  /// object, returning a nonnegative identifier to represent it. This function
-  /// takes a preferred alignment and a minimal alignment.
-  ///
-  int CreateStackObjectWithMinAlign(uint64_t Size, unsigned PrefAlignment,
-                        unsigned MinAlignment, bool isSS,
-                        bool MayNeedSP = false, const AllocaInst *Alloca = 0);
-
   /// CreateStackObject - Create a new statically sized stack object, returning
-  /// a nonnegative identifier to represent it. Will not emit an error when
-  /// Alignment can't be satisfied.
+  /// a nonnegative identifier to represent it.
   ///
   int CreateStackObject(uint64_t Size, unsigned Alignment, bool isSS,
-                        bool MayNeedSP = false, const AllocaInst *Alloca = 0) {
-    return CreateStackObjectWithMinAlign(Size, Alignment, 0, isSS,
-                                         MayNeedSP, Alloca);
-  }
+                        bool MayNeedSP = false, const AllocaInst *Alloca = 0);
 
   /// CreateSpillStackObject - Create a new statically sized stack object that
   /// represents a spill slot, returning a nonnegative identifier to represent
@@ -529,8 +517,7 @@ public:
   /// variable sized object is created, whether or not the index returned is
   /// actually used.
   ///
-  int CreateVariableSizedObject(unsigned PrefAlignment, unsigned MinAlignment,
-                                const AllocaInst *Alloca = 0);
+  int CreateVariableSizedObject(unsigned Alignment);
 
   /// getCalleeSavedInfo - Returns a reference to call saved info vector for the
   /// current function.
diff --git a/lib/CodeGen/MachineFunction.cpp b/lib/CodeGen/MachineFunction.cpp
index 1898222..5e04f2d 100644
--- a/lib/CodeGen/MachineFunction.cpp
+++ b/lib/CodeGen/MachineFunction.cpp
@@ -466,32 +466,24 @@ void MachineFrameInfo::ensureMaxAlignment(unsigned Align) {
 }
 
 /// clampStackAlignment - Clamp the alignment if requested and emit a warning.
-static inline unsigned clampStackAlignment(bool ShouldClamp, unsigned PrefAlign,
-                         unsigned MinAlign, unsigned StackAlign,
-                         const AllocaInst *Alloca = 0) {
-  if (!ShouldClamp || PrefAlign <= StackAlign)
-    return PrefAlign;
-  if (Alloca && MinAlign > StackAlign)
-    Alloca->getParent()->getContext().emitWarning(Alloca,
-        "Requested alignment exceeds the stack alignment!");
-  else
-    assert(MinAlign <= StackAlign &&
-           "Requested alignment exceeds the stack alignment!");
+static inline unsigned clampStackAlignment(bool ShouldClamp, unsigned Align,
+                                           unsigned StackAlign) {
+  if (!ShouldClamp || Align <= StackAlign)
+    return Align;
+  DEBUG(dbgs() << "Warning: requested alignment " << Align
+               << " exceeds the stack alignment " << StackAlign
+               << " when stack realignment is off" << '\n');
   return StackAlign;
 }
 
-/// CreateStackObjectWithMinAlign - Create a new statically sized stack
-/// object, returning a nonnegative identifier to represent it. This function
-/// takes a preferred alignment and a minimal alignment.
+/// CreateStackObject - Create a new statically sized stack object, returning
+/// a nonnegative identifier to represent it.
 ///
-int MachineFrameInfo::CreateStackObjectWithMinAlign(uint64_t Size,
-                          unsigned PrefAlignment, unsigned MinAlignment,
-                          bool isSS, bool MayNeedSP, const AllocaInst *Alloca) {
+int MachineFrameInfo::CreateStackObject(uint64_t Size, unsigned Alignment,
+                      bool isSS, bool MayNeedSP, const AllocaInst *Alloca) {
   assert(Size != 0 && "Cannot allocate zero size stack objects!");
-  unsigned Alignment = clampStackAlignment(
-                           !TFI.isStackRealignable() || !RealignOption,
-                           PrefAlignment, MinAlignment,
-                           TFI.getStackAlignment(), Alloca);
+  Alignment = clampStackAlignment(!TFI.isStackRealignable() || !RealignOption,
+                                  Alignment, TFI.getStackAlignment());
   Objects.push_back(StackObject(Size, Alignment, 0, false, isSS, MayNeedSP,
                                 Alloca));
   int Index = (int)Objects.size() - NumFixedObjects - 1;
@@ -507,8 +499,7 @@ int MachineFrameInfo::CreateStackObjectWithMinAlign(uint64_t Size,
 int MachineFrameInfo::CreateSpillStackObject(uint64_t Size,
                                              unsigned Alignment) {
   Alignment = clampStackAlignment(!TFI.isStackRealignable() || !RealignOption,
-                                  Alignment, 0,
-                                  TFI.getStackAlignment()); 
+                                  Alignment, TFI.getStackAlignment()); 
   CreateStackObject(Size, Alignment, true, false);
   int Index = (int)Objects.size() - NumFixedObjects - 1;
   ensureMaxAlignment(Alignment);
@@ -520,13 +511,10 @@ int MachineFrameInfo::CreateSpillStackObject(uint64_t Size,
 /// variable sized object is created, whether or not the index returned is
 /// actually used.
 ///
-int MachineFrameInfo::CreateVariableSizedObject(unsigned PrefAlignment,
-                        unsigned MinAlignment, const AllocaInst *Alloca) {
+int MachineFrameInfo::CreateVariableSizedObject(unsigned Alignment) {
   HasVarSizedObjects = true;
-  unsigned Alignment = clampStackAlignment(
-                           !TFI.isStackRealignable() || !RealignOption,
-                           PrefAlignment, MinAlignment,
-                           TFI.getStackAlignment(), Alloca); 
+  Alignment = clampStackAlignment(!TFI.isStackRealignable() || !RealignOption,
+                                  Alignment, TFI.getStackAlignment()); 
   Objects.push_back(StackObject(0, Alignment, 0, false, false, true, 0));
   ensureMaxAlignment(Alignment);
   return (int)Objects.size()-NumFixedObjects-1;
@@ -547,7 +535,7 @@ int MachineFrameInfo::CreateFixedObject(uint64_t Size, int64_t SPOffset,
   unsigned StackAlign = TFI.getStackAlignment();
   unsigned Align = MinAlign(SPOffset, StackAlign);
   Align = clampStackAlignment(!TFI.isStackRealignable() || !RealignOption,
-                              Align, 0, TFI.getStackAlignment()); 
+                              Align, TFI.getStackAlignment()); 
   Objects.insert(Objects.begin(), StackObject(Size, Align, SPOffset, Immutable,
                                               /*isSS*/   false,
                                               /*NeedSP*/ false,
diff --git a/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp b/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
index 229c50b..b46edad 100644
--- a/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
+++ b/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
@@ -95,8 +95,7 @@ void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf) {
            (TySize >= 8 && isa<ArrayType>(Ty) &&
             cast<ArrayType>(Ty)->getElementType()->isIntegerTy(8)));
         StaticAllocaMap[AI] =
-          MF->getFrameInfo()->CreateStackObjectWithMinAlign(TySize, Align,
-                                                AI->getAlignment(), false,
+          MF->getFrameInfo()->CreateStackObject(TySize, Align, false,
                                                 MayNeedSP, AI);
       }
 
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index e0d6643..405e1e8 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -3259,8 +3259,7 @@ void SelectionDAGBuilder::visitAlloca(const AllocaInst &I) {
 
   // Inform the Frame Information that we have just allocated a variable-sized
   // object.
-  FuncInfo.MF->getFrameInfo()->CreateVariableSizedObject(Align ? Align : 1,
-                                 I.getAlignment(), &I);
+  FuncInfo.MF->getFrameInfo()->CreateVariableSizedObject(Align ? Align : 1);
 }
 
 void SelectionDAGBuilder::visitLoad(const LoadInst &I) {
diff --git a/test/CodeGen/ARM/alloc-no-stack-realign-error.ll b/test/CodeGen/ARM/alloc-no-stack-realign-error.ll
deleted file mode 100644
index 9b4d12a..0000000
--- a/test/CodeGen/ARM/alloc-no-stack-realign-error.ll
+++ /dev/null
@@ -1,19 +0,0 @@
-; RUN: llc < %s -mtriple=armv7-apple-ios -O0 -realign-stack=0 2>&1 | FileCheck %s
-
-; rdar://12713765
-@T3_retval = common global <16 x float> zeroinitializer, align 16
-
-; If alignment for alloc is smaller than or equal to stack alignment, but the 
-; preferred type alignment is bigger, the alignment will be clamped.
-; If alignment for alloca is bigger than stack alignment, the compiler
-; will emit a warning.
-define void @test(<16 x float>* noalias sret %agg.result) nounwind ssp {
-entry:
-; CHECK: warning: Requested alignment exceeds the stack alignment!
- %retval = alloca <16 x float>, align 16
- %0 = load <16 x float>* @T3_retval, align 16
- store <16 x float> %0, <16 x float>* %retval
- %1 = load <16 x float>* %retval
- store <16 x float> %1, <16 x float>* %agg.result, align 16
- ret void
-}
diff --git a/test/CodeGen/ARM/alloc-no-stack-realign.ll b/test/CodeGen/ARM/alloc-no-stack-realign.ll
index 94adc9c..273041d 100644
--- a/test/CodeGen/ARM/alloc-no-stack-realign.ll
+++ b/test/CodeGen/ARM/alloc-no-stack-realign.ll
@@ -39,7 +39,7 @@ entry:
 ; NO-REALIGN: add [[R2:r[0-9]+]], [[R1:r[0-9]+]], #16
 ; NO-REALIGN: vst1.64
 ; NO-REALIGN: vst1.64
- %retval = alloca <16 x float>, align 4
+ %retval = alloca <16 x float>, align 16
  %0 = load <16 x float>* @T3_retval, align 16
  store <16 x float> %0, <16 x float>* %retval
  %1 = load <16 x float>* %retval