unsigned TemporaryReg = 0;
BitVector PopFriendly =
TRI.getAllocatableSet(MF, TRI.getRegClass(ARM::tGPRRegClassID));
+ // R7 may be used as a frame pointer, hence marked as not generally
+ // allocatable, however there's no reason to not use it as a temporary for
+ // restoring LR.
+ if (STI.useR7AsFramePointer())
+ PopFriendly.set(ARM::R7);
+
assert(PopFriendly.any() && "No allocatable pop-friendly register?!");
// Rebuild the GPRs from the high registers because they are removed
// form the GPR reg class for thumb1.
GPRsNoLRSP.reset(ARM::PC);
findTemporariesForLR(GPRsNoLRSP, PopFriendly, UsedRegs, PopReg, TemporaryReg);
- // If we couldn't find a pop-friendly register, restore LR before popping the
- // other callee-saved registers, so we can use one of them as a temporary.
+ // If we couldn't find a pop-friendly register, try restoring LR before
+ // popping the other callee-saved registers, so we could use one of them as a
+ // temporary.
bool UseLDRSP = false;
if (!PopReg && MBBI != MBB.begin()) {
auto PrevMBBI = MBBI;
PrevMBBI--;
if (PrevMBBI->getOpcode() == ARM::tPOP) {
- MBBI = PrevMBBI;
- UsedRegs.stepBackward(*MBBI);
+ UsedRegs.stepBackward(*PrevMBBI);
findTemporariesForLR(GPRsNoLRSP, PopFriendly, UsedRegs, PopReg, TemporaryReg);
- UseLDRSP = true;
+ if (PopReg) {
+ MBBI = PrevMBBI;
+ UseLDRSP = true;
+ }
}
}
--- /dev/null
+; RUN: llc -mtriple thumbv4t-eabi < %s | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-V4T
+; RUN: llc -mtriple armv8m.base-eabi < %s | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-V8M
+
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+
+; Function Attrs: nounwind
+define <4 x i32> @f() local_unnamed_addr #0 {
+entry:
+ %call = tail call i32 @h(i32 1)
+ %call1 = tail call <4 x i32> @g(i32 %call, i32 2, i32 3, i32 4)
+ ret <4 x i32> %call1
+; CHECK: ldr r7, [sp, #4]
+; CHECK-NEXT: mov lr, r7
+; CHECK-NEXT: pop {r7}
+; CHECK-NEXT: add sp, #4
+; CHECK-V47: bx lr
+; CHECK-V8M: b g
+}
+
+declare <4 x i32> @g(i32, i32, i32, i32) local_unnamed_addr
+
+declare i32 @h(i32) local_unnamed_addr
+
+attributes #0 = { "disable-tail-calls"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" }