processFunctionBeforeFrameFinalized(MachineFunction &MF,
RegScavenger *RS) const {
MachineFrameInfo &MFFrame = MF.getFrameInfo();
- uint64_t MaxReach = (MFFrame.estimateStackSize(MF) +
- SystemZMC::CallFrameSize * 2);
+ // Get the size of our stack frame to be allocated ...
+ uint64_t StackSize = (MFFrame.estimateStackSize(MF) +
+ SystemZMC::CallFrameSize);
+ // ... and the maximum offset we may need to reach into the
+ // caller's frame to access the save area or stack arguments.
+ int64_t MaxArgOffset = SystemZMC::CallFrameSize;
+ for (int I = MFFrame.getObjectIndexBegin(); I != 0; ++I)
+ if (MFFrame.getObjectOffset(I) >= 0) {
+ int64_t ArgOffset = SystemZMC::CallFrameSize +
+ MFFrame.getObjectOffset(I) +
+ MFFrame.getObjectSize(I);
+ MaxArgOffset = std::max(MaxArgOffset, ArgOffset);
+ }
+
+ uint64_t MaxReach = StackSize + MaxArgOffset;
if (!isUInt<12>(MaxReach)) {
// We may need register scavenging slots if some parts of the frame
// are outside the reach of an unsigned 12-bit displacement.
--- /dev/null
+; Test the allocation of emergency spill slots.
+;
+; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s
+
+; For frames of size less than 4096 - 2*160, no emercengy spill slot
+; is required. Check the maximum such case.
+define void @f1(i64 %x) {
+; CHECK-LABEL: f1:
+; CHECK: stg %r2, 160(%r15)
+; CHECK: br %r14
+ %y = alloca [471 x i64], align 8
+ %ptr = getelementptr inbounds [471 x i64], [471 x i64]* %y, i64 0, i64 0
+ store volatile i64 %x, i64* %ptr
+ ret void
+}
+
+; If the frame size is at least 4096 - 2*160, we do need the emergency
+; spill slots. Check the minimum such case.
+define void @f2(i64 %x) {
+; CHECK-LABEL: f2:
+; CHECK: stg %r2, 176(%r15)
+; CHECK: br %r14
+ %y = alloca [472 x i64], align 8
+ %ptr = getelementptr inbounds [472 x i64], [472 x i64]* %y, i64 0, i64 0
+ store volatile i64 %x, i64* %ptr
+ ret void
+}
+
+; However, if there are incoming stack arguments, those also need to be
+; in reach, so the maximum frame size without emergency spill slots is
+; 4096 - 2*160 - <size of incoming stack arguments>. Check the maximum
+; case where we still need no emergency spill slots ...
+define void @f3(i64 %x, i64 %r3, i64 %r4, i64 %r5, i64 %r6, i64 %stack) {
+; CHECK-LABEL: f3:
+; CHECK: stg %r2, 160(%r15)
+; CHECK: br %r14
+ %y = alloca [470 x i64], align 8
+ %ptr = getelementptr inbounds [470 x i64], [470 x i64]* %y, i64 0, i64 0
+ store volatile i64 %x, i64* %ptr
+ ret void
+}
+
+; ... and the minimum case where we do.
+define void @f4(i64 %x, i64 %r3, i64 %r4, i64 %r5, i64 %r6, i64 %stack) {
+; CHECK-LABEL: f4:
+; CHECK: stg %r2, 176(%r15)
+; CHECK: br %r14
+ %y = alloca [471 x i64], align 8
+ %ptr = getelementptr inbounds [471 x i64], [471 x i64]* %y, i64 0, i64 0
+ store volatile i64 %x, i64* %ptr
+ ret void
+}
+
+; Try again for the case of two stack arguments.
+; Check the maximum case where we still need no emergency spill slots ...
+define void @f5(i64 %x, i64 %r3, i64 %r4, i64 %r5, i64 %r6, i64 %stack1, i64 %stack2) {
+; CHECK-LABEL: f5:
+; CHECK: stg %r2, 160(%r15)
+; CHECK: br %r14
+ %y = alloca [469 x i64], align 8
+ %ptr = getelementptr inbounds [469 x i64], [469 x i64]* %y, i64 0, i64 0
+ store volatile i64 %x, i64* %ptr
+ ret void
+}
+
+; ... and the minimum case where we do.
+define void @f6(i64 %x, i64 %r3, i64 %r4, i64 %r5, i64 %r6, i64 %stack1, i64 %stack2) {
+; CHECK-LABEL: f6:
+; CHECK: stg %r2, 176(%r15)
+; CHECK: br %r14
+ %y = alloca [470 x i64], align 8
+ %ptr = getelementptr inbounds [470 x i64], [470 x i64]* %y, i64 0, i64 0
+ store volatile i64 %x, i64* %ptr
+ ret void
+}
+