[PATCH] D66730: Bug fix on function epilog optimization (ARM backend)

[Rainer Herbertz via Phabricator via llvm-commits]

rOptimizer updated this revision to Diff 217123.
rOptimizer added a comment.

- Bug fix on function epilog optimization (ARM backend)

Added regression test


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D66730/new/

https://reviews.llvm.org/D66730

Files:
  llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
  llvm/test/CodeGen/ARM/fold-stack-adjust.ll


Index: llvm/test/CodeGen/ARM/fold-stack-adjust.ll
===================================================================
--- llvm/test/CodeGen/ARM/fold-stack-adjust.ll
+++ llvm/test/CodeGen/ARM/fold-stack-adjust.ll
@@ -42,6 +42,19 @@
   ret void
 }
 
+define i32 @check_simple_ret() minsize {
+; CHECK-FNSTART-LABEL: check_simple_ret:
+; CHECK: push {r5, r6, r7, lr}
+; CHECK-NOT: sub sp,
+; ...
+; CHECK-NOT: add sp,
+; CHECK: pop {r2, r3, r7, pc}
+
+  %var = alloca i8, i32 8
+  call void @bar(i8* %var)
+  ret i32 0
+}
+
 define void @check_simple_too_big() minsize {
 ; CHECK-FNSTART-LABEL: check_simple_too_big:
 ; CHECK: push {r7, lr}
Index: llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
===================================================================
--- llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -2420,7 +2420,8 @@
     MachineOperand &MO = MI->getOperand(i);
     RegList.push_back(MO);
 
-    if (MO.isReg() && TRI->getEncodingValue(MO.getReg()) < FirstRegEnc)
+    if (MO.isReg() && !MO.isImplicit() &&
+        TRI->getEncodingValue(MO.getReg()) < FirstRegEnc)
       FirstRegEnc = TRI->getEncodingValue(MO.getReg());
   }
 
@@ -2430,7 +2431,7 @@
   for (int CurRegEnc = FirstRegEnc - 1; CurRegEnc >= 0 && RegsNeeded;
        --CurRegEnc) {
     unsigned CurReg = RegClass->getRegister(CurRegEnc);
-    if (IsT1PushPop && CurReg > ARM::R7)
+    if (IsT1PushPop && CurRegEnc > TRI->getEncodingValue(ARM::R7))
       continue;
     if (!IsPop) {
       // Pushing any register is completely harmless, mark the register involved


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