[Thumb1] LivePhysRegs to LiveRegUnits #84474
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@llvm/pr-subscribers-backend-arm Author: AtariDreams (AtariDreams) ChangesThis fixes a register allocation bug, because while r7 was marked as allowed to be used, LivePhysRegs always reported it as unavailable because it is reserved, despite this being an exception to the rule. Full diff: https://github.com/llvm/llvm-project/pull/84474.diff 2 Files Affected:
diff --git a/llvm/lib/Target/ARM/Thumb1FrameLowering.cpp b/llvm/lib/Target/ARM/Thumb1FrameLowering.cpp
index 0f4ece64bff532..a8cf036f363cdd 100644
--- a/llvm/lib/Target/ARM/Thumb1FrameLowering.cpp
+++ b/llvm/lib/Target/ARM/Thumb1FrameLowering.cpp
@@ -612,11 +612,11 @@ bool Thumb1FrameLowering::needPopSpecialFixUp(const MachineFunction &MF) const {
static void findTemporariesForLR(const BitVector &GPRsNoLRSP,
const BitVector &PopFriendly,
- const LivePhysRegs &UsedRegs, unsigned &PopReg,
+ const LiveRegUnits &UsedRegs, unsigned &PopReg,
unsigned &TmpReg, MachineRegisterInfo &MRI) {
PopReg = TmpReg = 0;
for (auto Reg : GPRsNoLRSP.set_bits()) {
- if (UsedRegs.available(MRI, Reg)) {
+ if (UsedRegs.available(Reg)) {
// Remember the first pop-friendly register and exit.
if (PopFriendly.test(Reg)) {
PopReg = Reg;
@@ -684,7 +684,7 @@ bool Thumb1FrameLowering::emitPopSpecialFixUp(MachineBasicBlock &MBB,
// Look for a temporary register to use.
// First, compute the liveness information.
const TargetRegisterInfo &TRI = *STI.getRegisterInfo();
- LivePhysRegs UsedRegs(TRI);
+ LiveRegUnits UsedRegs(TRI);
UsedRegs.addLiveOuts(MBB);
// The semantic of pristines changed recently and now,
// the callee-saved registers that are touched in the function
diff --git a/llvm/test/CodeGen/Thumb/PR35481.ll b/llvm/test/CodeGen/Thumb/PR35481.ll
index ad3215ecb94952..e48d1547782caf 100644
--- a/llvm/test/CodeGen/Thumb/PR35481.ll
+++ b/llvm/test/CodeGen/Thumb/PR35481.ll
@@ -18,11 +18,10 @@ define <4 x i32> @f() local_unnamed_addr #0 {
; CHECK-V4T-NEXT: movs r2, #3
; CHECK-V4T-NEXT: movs r3, #4
; CHECK-V4T-NEXT: bl g
+; CHECK-V4T-NEXT: ldr r7, [sp, #4]
+; CHECK-V4T-NEXT: mov lr, r7
; CHECK-V4T-NEXT: pop {r7}
-; CHECK-V4T-NEXT: mov r12, r0
-; CHECK-V4T-NEXT: pop {r0}
-; CHECK-V4T-NEXT: mov lr, r0
-; CHECK-V4T-NEXT: mov r0, r12
+; CHECK-V4T-NEXT: add sp, #4
; CHECK-V4T-NEXT: bx lr
;
; CHECK-V8M-LABEL: f:
@@ -36,11 +35,10 @@ define <4 x i32> @f() local_unnamed_addr #0 {
; CHECK-V8M-NEXT: movs r1, #2
; CHECK-V8M-NEXT: movs r2, #3
; CHECK-V8M-NEXT: movs r3, #4
+; CHECK-V8M-NEXT: ldr r7, [sp, #4]
+; CHECK-V8M-NEXT: mov lr, r7
; CHECK-V8M-NEXT: pop {r7}
-; CHECK-V8M-NEXT: mov r12, r0
-; CHECK-V8M-NEXT: pop {r0}
-; CHECK-V8M-NEXT: mov lr, r0
-; CHECK-V8M-NEXT: mov r0, r12
+; CHECK-V8M-NEXT: add sp, #4
; CHECK-V8M-NEXT: b g
entry:
%call = tail call i32 @h(i32 1)
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✅ With the latest revision this PR passed the C/C++ code formatter. |
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Please fix the commit message (which is taken from the first comment in the thread when I hit "squash and merge"). Also, your email address is currently hidden (see https://discourse.llvm.org/t/hidden-emails-on-github-should-we-do-something-about-it/74223/) |
Done! |
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Email address is still hidden. Quoting the automated message that's supposed to trigger (not sure why it didn't trigger here):
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@efriedma-quic Fixed |
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Still hidden. |
Nope. See the commit itself. |
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The "squash and merge" button in the GitHub UI only depends on your GitHub account settings, not the "author" line in the commit. (I don't really want to cherry-pick the patch manually.) |
My github account setting changed to my public email so I don't understand |
There's only one commit so you just have to merge it. |
There's a checkbox "Keep my email addresses private" at https://github.com/settings/emails . If you have it checked, operations through the GitHub UI set the the author email address to "[email protected]", instead of whatever you have set.
If it was just the one time, I'd just do it, but this is going to be a repeating problem for anyone merging commits on your behalf. |
Fixed! |
This removes the r7 exception because otherwise, LiveRegUnits will try to use that register.
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Remove r7 exception because it messes up profilers and others. |
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/pull-request 9669aba |
This removes the r7 exception because otherwise, LiveRegUnits will try to use that register.