xref: /freebsd-9.3-release/contrib/llvm/patches/patch-r263312-llvm-r202930-fix-alloca-esi-clobber.diff

Pull in r202930 from upstream llvm trunk (by Hans Wennborg):

  Check for dynamic allocas and inline asm that clobbers sp before building
  selection dag (PR19012)

  In X86SelectionDagInfo::EmitTargetCodeForMemcpy we check with MachineFrameInfo
  to make sure that ESI isn't used as a base pointer register before we choose to
  emit rep movs (which clobbers esi).

  The problem is that MachineFrameInfo wouldn't know about dynamic allocas or
  inline asm that clobbers the stack pointer until SelectionDAGBuilder has
  encountered them.

  This patch fixes the problem by checking for such things when building the
  FunctionLoweringInfo.

  Differential Revision: http://llvm-reviews.chandlerc.com/D2954

Introduced here: http://svn.freebsd.org/changeset/base/263312

Index: lib/CodeGen/MachineFunction.cpp
===================================================================
--- lib/CodeGen/MachineFunction.cpp
+++ lib/CodeGen/MachineFunction.cpp
@@ -525,13 +525,14 @@ int MachineFrameInfo::CreateSpillStackObject(uint6
 /// variable sized object is created, whether or not the index returned is
 /// actually used.
 ///
-int MachineFrameInfo::CreateVariableSizedObject(unsigned Alignment) {
+int MachineFrameInfo::CreateVariableSizedObject(unsigned Alignment,
+                                                const AllocaInst *Alloca) {
   HasVarSizedObjects = true;
   Alignment =
     clampStackAlignment(!getFrameLowering()->isStackRealignable() ||
                           !RealignOption,
                         Alignment, getFrameLowering()->getStackAlignment()); 
-  Objects.push_back(StackObject(0, Alignment, 0, false, false, true, 0));
+  Objects.push_back(StackObject(0, Alignment, 0, false, false, true, Alloca));
   ensureMaxAlignment(Alignment);
   return (int)Objects.size()-NumFixedObjects-1;
 }
Index: lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -419,7 +419,7 @@ bool SelectionDAGISel::runOnMachineFunction(Machin
   SplitCriticalSideEffectEdges(const_cast<Function&>(Fn), this);
 
   CurDAG->init(*MF, TTI, TLI);
-  FuncInfo->set(Fn, *MF);
+  FuncInfo->set(Fn, *MF, CurDAG);
 
   if (UseMBPI && OptLevel != CodeGenOpt::None)
     FuncInfo->BPI = &getAnalysis<BranchProbabilityInfo>();
@@ -429,7 +429,6 @@ bool SelectionDAGISel::runOnMachineFunction(Machin
   SDB->init(GFI, *AA, LibInfo);
 
   MF->setHasInlineAsm(false);
-  MF->getFrameInfo()->setHasInlineAsmWithSPAdjust(false);
 
   SelectAllBasicBlocks(Fn);
 
Index: lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
+++ lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
@@ -33,6 +33,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetFrameLowering.h"
 #include "llvm/Target/TargetLowering.h"
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/Target/TargetRegisterInfo.h"
@@ -55,7 +56,8 @@ static bool isUsedOutsideOfDefiningBlock(const Ins
   return false;
 }
 
-void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf) {
+void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf,
+                               SelectionDAG *DAG) {
   const TargetLowering *TLI = TM.getTargetLowering();
 
   Fn = &fn;
@@ -100,6 +102,43 @@ static bool isUsedOutsideOfDefiningBlock(const Ins
   for (; BB != EB; ++BB)
     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
          I != E; ++I) {
+      // Look for dynamic allocas.
+      if (const AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
+        if (!AI->isStaticAlloca()) {
+          unsigned Align = std::max(
+              (unsigned)TLI->getDataLayout()->getPrefTypeAlignment(
+                AI->getAllocatedType()),
+              AI->getAlignment());
+          unsigned StackAlign = TM.getFrameLowering()->getStackAlignment();
+          if (Align <= StackAlign)
+            Align = 0;
+          // Inform the Frame Information that we have variable-sized objects.
+          MF->getFrameInfo()->CreateVariableSizedObject(Align ? Align : 1, AI);
+        }
+      }
+
+      // Look for inline asm that clobbers the SP register.
+      if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
+        ImmutableCallSite CS(I);
+        if (const InlineAsm *IA = dyn_cast<InlineAsm>(CS.getCalledValue())) {
+          unsigned SP = TLI->getStackPointerRegisterToSaveRestore();
+          std::vector<TargetLowering::AsmOperandInfo> Ops =
+            TLI->ParseConstraints(CS);
+          for (size_t I = 0, E = Ops.size(); I != E; ++I) {
+            TargetLowering::AsmOperandInfo &Op = Ops[I];
+            if (Op.Type == InlineAsm::isClobber) {
+              // Clobbers don't have SDValue operands, hence SDValue().
+              TLI->ComputeConstraintToUse(Op, SDValue(), DAG);
+              std::pair<unsigned, const TargetRegisterClass*> PhysReg =
+                TLI->getRegForInlineAsmConstraint(Op.ConstraintCode,
+                                                  Op.ConstraintVT);
+              if (PhysReg.first == SP)
+                MF->getFrameInfo()->setHasInlineAsmWithSPAdjust(true);
+            }
+          }
+        }
+      }
+
       // Mark values used outside their block as exported, by allocating
       // a virtual register for them.
       if (isUsedOutsideOfDefiningBlock(I))
Index: lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -860,10 +860,10 @@ void RegsForValue::AddInlineAsmOperands(unsigned C
       unsigned TheReg = Regs[Reg++];
       Ops.push_back(DAG.getRegister(TheReg, RegisterVT));
 
-      // Notice if we clobbered the stack pointer.  Yes, inline asm can do this.
       if (TheReg == SP && Code == InlineAsm::Kind_Clobber) {
-        MachineFrameInfo *MFI = DAG.getMachineFunction().getFrameInfo();
-        MFI->setHasInlineAsmWithSPAdjust(true);
+        // If we clobbered the stack pointer, MFI should know about it.
+        assert(DAG.getMachineFunction().getFrameInfo()->
+            hasInlineAsmWithSPAdjust());
       }
     }
   }
@@ -3378,9 +3378,7 @@ void SelectionDAGBuilder::visitAlloca(const Alloca
   setValue(&I, DSA);
   DAG.setRoot(DSA.getValue(1));
 
-  // Inform the Frame Information that we have just allocated a variable-sized
-  // object.
-  FuncInfo.MF->getFrameInfo()->CreateVariableSizedObject(Align ? Align : 1);
+  assert(FuncInfo.MF->getFrameInfo()->hasVarSizedObjects());
 }
 
 void SelectionDAGBuilder::visitLoad(const LoadInst &I) {
Index: test/CodeGen/X86/stack-align-memcpy.ll
===================================================================
--- test/CodeGen/X86/stack-align-memcpy.ll
+++ test/CodeGen/X86/stack-align-memcpy.ll
@@ -2,6 +2,9 @@
 
 %struct.foo = type { [88 x i8] }
 
+declare void @bar(i8* nocapture, %struct.foo* align 4 byval) nounwind
+declare void @baz(i8*) nounwind
+
 ; PR15249
 ; We can't use rep;movsl here because it clobbers the base pointer in %esi.
 define void @test1(%struct.foo* nocapture %x, i32 %y) nounwind {
@@ -15,4 +18,26 @@ define void @test1(%struct.foo* nocapture %x, i32
 ; CHECK-NOT: rep;movsl
 }
 
-declare void @bar(i8* nocapture, %struct.foo* align 4 byval) nounwind
+; PR19012
+; Also don't clobber %esi if the dynamic alloca comes after the memcpy.
+define void @test2(%struct.foo* nocapture %x, i32 %y, i8* %z) nounwind {
+  call void @bar(i8* %z, %struct.foo* align 4 byval %x)
+  %dynalloc = alloca i8, i32 %y, align 1
+  call void @baz(i8* %dynalloc)
+  ret void
+
+; CHECK-LABEL: test2:
+; CHECK: movl %esp, %esi
+; CHECK-NOT: rep;movsl
+}
+
+; Check that we do use rep movs if we make the alloca static.
+define void @test3(%struct.foo* nocapture %x, i32 %y, i8* %z) nounwind {
+  call void @bar(i8* %z, %struct.foo* align 4 byval %x)
+  %statalloc = alloca i8, i32 8, align 1
+  call void @baz(i8* %statalloc)
+  ret void
+
+; CHECK-LABEL: test3:
+; CHECK: rep;movsl
+}
Index: test/CodeGen/X86/inline-asm-sp-clobber-memcpy.ll
===================================================================
--- test/CodeGen/X86/inline-asm-sp-clobber-memcpy.ll
+++ test/CodeGen/X86/inline-asm-sp-clobber-memcpy.ll
@@ -0,0 +1,17 @@
+; RUN: llc < %s -force-align-stack -mtriple i386-apple-darwin -mcpu=i486 | FileCheck %s
+
+%struct.foo = type { [88 x i8] }
+
+declare void @bar(i8* nocapture, %struct.foo* align 4 byval) nounwind
+
+; PR19012
+; Don't clobber %esi if we have inline asm that clobbers %esp.
+define void @test1(%struct.foo* nocapture %x, i32 %y, i8* %z) nounwind {
+  call void @bar(i8* %z, %struct.foo* align 4 byval %x)
+  call void asm sideeffect inteldialect "xor esp, esp", "=*m,~{flags},~{esp},~{esp},~{dirflag},~{fpsr},~{flags}"(i8* %z)
+  ret void
+
+; CHECK-LABEL: test1:
+; CHECK: movl %esp, %esi
+; CHECK-NOT: rep;movsl
+}
Index: include/llvm/CodeGen/FunctionLoweringInfo.h
===================================================================
--- include/llvm/CodeGen/FunctionLoweringInfo.h
+++ include/llvm/CodeGen/FunctionLoweringInfo.h
@@ -41,6 +41,7 @@ class MachineBasicBlock;
 class MachineFunction;
 class MachineModuleInfo;
 class MachineRegisterInfo;
+class SelectionDAG;
 class TargetLowering;
 class Value;
 
@@ -125,7 +126,7 @@ class FunctionLoweringInfo {
   /// set - Initialize this FunctionLoweringInfo with the given Function
   /// and its associated MachineFunction.
   ///
-  void set(const Function &Fn, MachineFunction &MF);
+  void set(const Function &Fn, MachineFunction &MF, SelectionDAG *DAG);
 
   /// clear - Clear out all the function-specific state. This returns this
   /// FunctionLoweringInfo to an empty state, ready to be used for a
Index: include/llvm/CodeGen/MachineFrameInfo.h
===================================================================
--- include/llvm/CodeGen/MachineFrameInfo.h
+++ include/llvm/CodeGen/MachineFrameInfo.h
@@ -244,6 +244,7 @@ class MachineFrameInfo {
     LocalFrameSize = 0;
     LocalFrameMaxAlign = 0;
     UseLocalStackAllocationBlock = false;
+    HasInlineAsmWithSPAdjust = false;
   }
 
   /// hasStackObjects - Return true if there are any stack objects in this
@@ -529,7 +530,7 @@ class MachineFrameInfo {
   /// variable sized object is created, whether or not the index returned is
   /// actually used.
   ///
-  int CreateVariableSizedObject(unsigned Alignment);
+  int CreateVariableSizedObject(unsigned Alignment, const AllocaInst *Alloca);
 
   /// getCalleeSavedInfo - Returns a reference to call saved info vector for the
   /// current function.