[PATCH] D46777: [ARM] Back up R4 and LR if calling the stack probe function
Martin Storsjö via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Fri May 11 23:42:05 PDT 2018
mstorsjo updated this revision to Diff 146463.
mstorsjo added a comment.
Simplified the estimate, elaborated the comment a little.
https://reviews.llvm.org/D46777
Files:
lib/Target/ARM/ARMFrameLowering.cpp
test/CodeGen/ARM/Windows/chkstk-movw-movt-isel.ll
Index: test/CodeGen/ARM/Windows/chkstk-movw-movt-isel.ll
===================================================================
--- test/CodeGen/ARM/Windows/chkstk-movw-movt-isel.ll
+++ test/CodeGen/ARM/Windows/chkstk-movw-movt-isel.ll
@@ -18,7 +18,7 @@
}
; 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*}}
Index: lib/Target/ARM/ARMFrameLowering.cpp
===================================================================
--- lib/Target/ARM/ARMFrameLowering.cpp
+++ lib/Target/ARM/ARMFrameLowering.cpp
@@ -1616,9 +1616,20 @@
// since it's not always possible to restore sp from fp in a single
// instruction.
// FIXME: It will be better just to find spare register here.
- if (AFI->isThumb2Function() &&
- (MFI.hasVarSizedObjects() || RegInfo->needsStackRealignment(MF)))
- SavedRegs.set(ARM::R4);
+ if (AFI->isThumb2Function()) {
+ if (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.
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