It's not safe to fold a load from GV stub or constantpool into a two-address use.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@49002 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 51 insertions, 2 deletions

diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 621c83df7a..f29b61b59f 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -757,8 +757,9 @@ bool LiveIntervals::tryFoldMemoryOperand(MachineInstr* &MI,
   if (FilterFoldedOps(MI, Ops, MRInfo, FoldOps))
     return false;
 
-  // Can't fold a load from fixed stack slot into a two address instruction.
-  if (isSS && DefMI && (MRInfo & VirtRegMap::isMod))
+  // The only time it's safe to fold into a two address instruction is when
+  // it's folding reload and spill from / into a spill stack slot.
+  if (DefMI && (MRInfo & VirtRegMap::isMod))
     return false;
 
   MachineInstr *fmi = isSS ? tii_->foldMemoryOperand(*mf_, MI, FoldOps, Slot)
diff --git a/lib/Target/X86/X86InstrInfo.cpp b/lib/Target/X86/X86InstrInfo.cpp
index ffe2083322..8a5464567f 100644
--- a/lib/Target/X86/X86InstrInfo.cpp
+++ b/lib/Target/X86/X86InstrInfo.cpp
@@ -1825,7 +1825,15 @@ X86InstrInfo::foldMemoryOperand(MachineInstr *MI, unsigned i,
       MI->getOperand(0).getReg() == MI->getOperand(1).getReg()) { 
     OpcodeTablePtr = &RegOp2MemOpTable2Addr;
     isTwoAddrFold = true;
+    // Can't write back to CPI or a GV stub.
+    if (MOs[3].isCPI() ||
+        (MOs[3].isGlobal() && isGVStub(MOs[3].getGlobal(), TM)))
+      return NULL;
   } else if (i == 0) { // If operand 0
+    // Can't write back to CPI or a GV stub.
+    if (MOs[3].isCPI() ||
+        (MOs[3].isGlobal() && isGVStub(MOs[3].getGlobal(), TM)))
+      return NULL;
     if (MI->getOpcode() == X86::MOV16r0)
       NewMI = MakeM0Inst(*this, X86::MOV16mi, MOs, MI);
     else if (MI->getOpcode() == X86::MOV32r0)
diff --git a/test/CodeGen/X86/2008-03-31-SpillerFoldingBug.ll b/test/CodeGen/X86/2008-03-31-SpillerFoldingBug.ll
new file mode 100644
index 0000000000..83e1d60fcb
--- /dev/null
+++ b/test/CodeGen/X86/2008-03-31-SpillerFoldingBug.ll
@@ -0,0 +1,40 @@
+; RUN: llvm-as < %s | llc -mtriple=i386-apple-darwin -relocation-model=pic -disable-fp-elim | grep add | grep 12 | not grep non_lazy_ptr
+; Don't fold re-materialized load into a two address instruction
+
+	%"struct.Smarts::Runnable" = type { i32 (...)**, i32 }
+	%struct.__sbuf = type { i8*, i32 }
+	%"struct.std::ios_base" = type { i32 (...)**, i32, i32, i32, i32, i32, %"struct.std::ios_base::_Callback_list"*, %struct.__sbuf, [8 x %struct.__sbuf], i32, %struct.__sbuf*, %"struct.std::locale" }
+	%"struct.std::ios_base::_Callback_list" = type { %"struct.std::ios_base::_Callback_list"*, void (i32, %"struct.std::ios_base"*, i32)*, i32, i32 }
+	%"struct.std::locale" = type { %"struct.std::locale::_Impl"* }
+	%"struct.std::locale::_Impl" = type { i32, %"struct.Smarts::Runnable"**, i32, %"struct.Smarts::Runnable"**, i8** }
+@_ZTVSt9basic_iosIcSt11char_traitsIcEE = external constant [4 x i32 (...)*]		; <[4 x i32 (...)*]*> [#uses=1]
+@_ZTTSt19basic_ostringstreamIcSt11char_traitsIcESaIcEE = external constant [4 x i8*]		; <[4 x i8*]*> [#uses=1]
+@_ZTVSt19basic_ostringstreamIcSt11char_traitsIcESaIcEE = external constant [10 x i32 (...)*]		; <[10 x i32 (...)*]*> [#uses=2]
+@_ZTVSt15basic_streambufIcSt11char_traitsIcEE = external constant [16 x i32 (...)*]		; <[16 x i32 (...)*]*> [#uses=1]
+@_ZTVSt15basic_stringbufIcSt11char_traitsIcESaIcEE = external constant [16 x i32 (...)*]		; <[16 x i32 (...)*]*> [#uses=1]
+
+define void @_GLOBAL__I__ZN5Pooma5pinfoE() nounwind  {
+entry:
+	store i32 (...)** getelementptr ([10 x i32 (...)*]* @_ZTVSt19basic_ostringstreamIcSt11char_traitsIcESaIcEE, i32 0, i32 8), i32 (...)*** null, align 4
+	%tmp96.i.i142.i = call i8* @_Znwm( i32 180 ) nounwind 		; <i8*> [#uses=2]
+	call void @_ZNSt8ios_baseC2Ev( %"struct.std::ios_base"* null ) nounwind 
+	store i32 (...)** getelementptr ([4 x i32 (...)*]* @_ZTVSt9basic_iosIcSt11char_traitsIcEE, i32 0, i32 2), i32 (...)*** null, align 4
+	store i32 (...)** null, i32 (...)*** null, align 4
+	%ctg2242.i.i163.i = getelementptr i8* %tmp96.i.i142.i, i32 0		; <i8*> [#uses=1]
+	%tmp150.i.i164.i = load i8** getelementptr ([4 x i8*]* @_ZTTSt19basic_ostringstreamIcSt11char_traitsIcESaIcEE, i32 0, i64 2), align 4		; <i8*> [#uses=1]
+	%tmp150151.i.i165.i = bitcast i8* %tmp150.i.i164.i to i32 (...)**		; <i32 (...)**> [#uses=1]
+	%tmp153.i.i166.i = bitcast i8* %ctg2242.i.i163.i to i32 (...)***		; <i32 (...)***> [#uses=1]
+	store i32 (...)** %tmp150151.i.i165.i, i32 (...)*** %tmp153.i.i166.i, align 4
+	%tmp159.i.i167.i = bitcast i8* %tmp96.i.i142.i to i32 (...)***		; <i32 (...)***> [#uses=1]
+	store i32 (...)** getelementptr ([10 x i32 (...)*]* @_ZTVSt19basic_ostringstreamIcSt11char_traitsIcESaIcEE, i32 0, i32 3), i32 (...)*** %tmp159.i.i167.i, align 4
+	store i32 (...)** getelementptr ([16 x i32 (...)*]* @_ZTVSt15basic_streambufIcSt11char_traitsIcEE, i32 0, i32 2), i32 (...)*** null, align 4
+	call void @_ZNSt6localeC1Ev( %"struct.std::locale"* null ) nounwind 
+	store i32 (...)** getelementptr ([16 x i32 (...)*]* @_ZTVSt15basic_stringbufIcSt11char_traitsIcESaIcEE, i32 0, i32 2), i32 (...)*** null, align 4
+	unreachable
+}
+
+declare i8* @_Znwm(i32)
+
+declare void @_ZNSt8ios_baseC2Ev(%"struct.std::ios_base"*)
+
+declare void @_ZNSt6localeC1Ev(%"struct.std::locale"*) nounwind