[Sparc] Account for bias in stack readjustment
Summary: This was broken long ago in D12208, which failed to account for
the fact that 64-bit SPARC uses a stack bias of 2047, and it is the
*unbiased* value which should be aligned, not the biased one. This was
seen to be an issue with Rust.
Patch by: jrtc27 (James Clarke)
Reviewers: jyknight, venkatra
Reviewed By: jyknight
Subscribers: jacob_hansen, JDevlieghere, fhahn, fedor.sergeev, llvm-commits
Differential Revision: https://reviews.llvm.org/D39425
llvm-svn: 323643
diff --git a/llvm/lib/Target/Sparc/SparcFrameLowering.cpp b/llvm/lib/Target/Sparc/SparcFrameLowering.cpp
index 9864aa3..9f6c7d6 100644
--- a/llvm/lib/Target/Sparc/SparcFrameLowering.cpp
+++ b/llvm/lib/Target/Sparc/SparcFrameLowering.cpp
@@ -88,10 +88,11 @@
assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
MachineFrameInfo &MFI = MF.getFrameInfo();
+ const SparcSubtarget &Subtarget = MF.getSubtarget<SparcSubtarget>();
const SparcInstrInfo &TII =
- *static_cast<const SparcInstrInfo *>(MF.getSubtarget().getInstrInfo());
+ *static_cast<const SparcInstrInfo *>(Subtarget.getInstrInfo());
const SparcRegisterInfo &RegInfo =
- *static_cast<const SparcRegisterInfo *>(MF.getSubtarget().getRegisterInfo());
+ *static_cast<const SparcRegisterInfo *>(Subtarget.getRegisterInfo());
MachineBasicBlock::iterator MBBI = MBB.begin();
// Debug location must be unknown since the first debug location is used
// to determine the end of the prologue.
@@ -141,7 +142,7 @@
// Adds the SPARC subtarget-specific spill area to the stack
// size. Also ensures target-required alignment.
- NumBytes = MF.getSubtarget<SparcSubtarget>().getAdjustedFrameSize(NumBytes);
+ NumBytes = Subtarget.getAdjustedFrameSize(NumBytes);
// Finally, ensure that the size is sufficiently aligned for the
// data on the stack.
@@ -176,9 +177,27 @@
.addCFIIndex(CFIIndex);
if (NeedsStackRealignment) {
- // andn %o6, MaxAlign-1, %o6
+ int64_t Bias = Subtarget.getStackPointerBias();
+ unsigned regUnbiased;
+ if (Bias) {
+ // This clobbers G1 which we always know is available here.
+ regUnbiased = SP::G1;
+ // add %o6, BIAS, %g1
+ BuildMI(MBB, MBBI, dl, TII.get(SP::ADDri), regUnbiased)
+ .addReg(SP::O6).addImm(Bias);
+ } else
+ regUnbiased = SP::O6;
+
+ // andn %regUnbiased, MaxAlign-1, %regUnbiased
int MaxAlign = MFI.getMaxAlignment();
- BuildMI(MBB, MBBI, dl, TII.get(SP::ANDNri), SP::O6).addReg(SP::O6).addImm(MaxAlign - 1);
+ BuildMI(MBB, MBBI, dl, TII.get(SP::ANDNri), regUnbiased)
+ .addReg(regUnbiased).addImm(MaxAlign - 1);
+
+ if (Bias) {
+ // add %g1, -BIAS, %o6
+ BuildMI(MBB, MBBI, dl, TII.get(SP::ADDri), SP::O6)
+ .addReg(regUnbiased).addImm(-Bias);
+ }
}
}