[llvm] r332298 - [ARM] Back up R4 and LR if calling the stack probe function

[Martin Storsjo via llvm-commits]

Author: mstorsjo
Date: Mon May 14 14:32:52 2018
New Revision: 332298

URL: http://llvm.org/viewvc/llvm-project?rev=332298&view=rev
Log:
[ARM] Back up R4 and LR if calling the stack probe function

Differential Revision: https://reviews.llvm.org/D46777

Modified:
    llvm/trunk/lib/Target/ARM/ARMFrameLowering.cpp
    llvm/trunk/test/CodeGen/ARM/Windows/chkstk-movw-movt-isel.ll

Modified: llvm/trunk/lib/Target/ARM/ARMFrameLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMFrameLowering.cpp?rev=332298&r1=332297&r2=332298&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMFrameLowering.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMFrameLowering.cpp Mon May 14 14:32:52 2018
@@ -1620,6 +1620,17 @@ void ARMFrameLowering::determineCalleeSa
       (MFI.hasVarSizedObjects() || RegInfo->needsStackRealignment(MF)))
     SavedRegs.set(ARM::R4);
 
+  // If a stack probe will be emitted, spill R4 and LR, since they are
+  // clobbered by the stack probe call.
+  // This estimate should be a safe, conservative estimate. The actual
+  // stack probe is enabled based on the size of the local objects;
+  // this estimate also includes the varargs store size.
+  if (STI.isTargetWindows() &&
+      WindowsRequiresStackProbe(MF, MFI.estimateStackSize(MF))) {
+    SavedRegs.set(ARM::R4);
+    SavedRegs.set(ARM::LR);
+  }
+
   if (AFI->isThumb1OnlyFunction()) {
     // Spill LR if Thumb1 function uses variable length argument lists.
     if (AFI->getArgRegsSaveSize() > 0)

Modified: llvm/trunk/test/CodeGen/ARM/Windows/chkstk-movw-movt-isel.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/Windows/chkstk-movw-movt-isel.ll?rev=332298&r1=332297&r2=332298&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/Windows/chkstk-movw-movt-isel.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/Windows/chkstk-movw-movt-isel.ll Mon May 14 14:32:52 2018
@@ -18,7 +18,7 @@ entry:
 }
 
 ; CHECK-LABEL: isel
-; CHECK: push {r4, r5}
+; CHECK: push {r4, r5, r6, lr}
 ; CHECK: movw r12, #0
 ; CHECK: movt r12, #0
 ; CHECK: movw r4, #{{\d*}}