[Sparc] Flush register windows for @llvm.returnaddress(1)

Summary: When @llvm.returnaddress is called with a value higher than 0
it needs to read from the call stack to get the return address. This
means that the register windows needs to be flushed to the stack to
guarantee that the data read is valid. For values higher than 1 this
is done indirectly by the call to getFRAMEADDR(), but not for the value 1.

Reviewers: jyknight, venkatra

Reviewed By: jyknight

Subscribers: fedor.sergeev, jrtc27, llvm-commits

Differential Revision: https://reviews.llvm.org/D48636

llvm-svn: 340003

diff --git a/llvm/lib/Target/Sparc/SparcISelLowering.cpp b/llvm/lib/Target/Sparc/SparcISelLowering.cpp
index b04c6b1..9a4f67e 100644 (file)
--- a/llvm/lib/Target/Sparc/SparcISelLowering.cpp
+++ b/llvm/lib/Target/Sparc/SparcISelLowering.cpp
@@ -2666,7 +2666,8 @@ static SDValue getFLUSHW(SDValue Op, SelectionDAG &DAG) {
 }
 
 static SDValue getFRAMEADDR(uint64_t depth, SDValue Op, SelectionDAG &DAG,
-                            const SparcSubtarget *Subtarget) {
+                            const SparcSubtarget *Subtarget,
+                            bool AlwaysFlush = false) {
   MachineFrameInfo &MFI = DAG.getMachineFunction().getFrameInfo();
   MFI.setFrameAddressIsTaken(true);
 
@@ -2676,17 +2677,11 @@ static SDValue getFRAMEADDR(uint64_t depth, SDValue Op, SelectionDAG &DAG,
   unsigned stackBias = Subtarget->getStackPointerBias();
 
   SDValue FrameAddr;
-
-  if (depth == 0) {
-    FrameAddr = DAG.getCopyFromReg(DAG.getEntryNode(), dl, FrameReg, VT);
-    if (Subtarget->is64Bit())
-      FrameAddr = DAG.getNode(ISD::ADD, dl, VT, FrameAddr,
-                              DAG.getIntPtrConstant(stackBias, dl));
-    return FrameAddr;
-  }
+  SDValue Chain;
 
   // flush first to make sure the windowed registers' values are in stack
-  SDValue Chain = getFLUSHW(Op, DAG);
+  Chain = (depth || AlwaysFlush) ? getFLUSHW(Op, DAG) : DAG.getEntryNode();
+
   FrameAddr = DAG.getCopyFromReg(Chain, dl, FrameReg, VT);
 
   unsigned Offset = (Subtarget->is64Bit()) ? (stackBias + 112) : 56;
@@ -2735,7 +2730,7 @@ static SDValue LowerRETURNADDR(SDValue Op, SelectionDAG &DAG,
   }
 
   // Need frame address to find return address of the caller.
-  SDValue FrameAddr = getFRAMEADDR(depth - 1, Op, DAG, Subtarget);
+  SDValue FrameAddr = getFRAMEADDR(depth - 1, Op, DAG, Subtarget, true);
 
   unsigned Offset = (Subtarget->is64Bit()) ? 120 : 60;
   SDValue Ptr = DAG.getNode(ISD::ADD,

diff --git a/llvm/test/CodeGen/SPARC/2011-01-11-FrameAddr.ll b/llvm/test/CodeGen/SPARC/2011-01-11-FrameAddr.ll
index 0d0ce0e..1c55966 100644 (file)
--- a/llvm/test/CodeGen/SPARC/2011-01-11-FrameAddr.ll
+++ b/llvm/test/CodeGen/SPARC/2011-01-11-FrameAddr.ll
@@ -96,4 +96,22 @@ entry:
   ret i8* %0
 }
 
+define i8* @retaddr3() nounwind readnone {
+entry:
+;V8-LABEL: retaddr3:
+;V8: ta 3
+;V8: ld [%fp+60], {{.+}}
+
+;V9-LABEL: retaddr3:
+;V9: flushw
+;V9: ld [%fp+60], {{.+}}
+
+;SPARC64-LABEL: retaddr3
+;SPARC64:       flushw
+;SPARC64: ldx [%fp+2167],     %[[R0:[goli][0-7]]]
+
+  %0 = tail call i8* @llvm.returnaddress(i32 1)
+  ret i8* %0
+}
+
 declare i8* @llvm.returnaddress(i32) nounwind readnone