[PATCH] D54173: [ARM] Add MemOp into LDRcp to enable removing

[Eli Friedman via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL346563: [ARM] Add MemOperand to LDRcp to enable DCE. (authored by efriedma, committed by ).

Changed prior to commit:
  https://reviews.llvm.org/D54173?vs=173195&id=173455#toc

Repository:
  rL LLVM

https://reviews.llvm.org/D54173

Files:
  llvm/trunk/lib/Target/ARM/ARMFastISel.cpp
  llvm/trunk/test/CodeGen/ARM/ldrcppic.ll


Index: llvm/trunk/test/CodeGen/ARM/ldrcppic.ll
===================================================================
--- llvm/trunk/test/CodeGen/ARM/ldrcppic.ll
+++ llvm/trunk/test/CodeGen/ARM/ldrcppic.ll
@@ -0,0 +1,56 @@
+; The failure is caused by ARM LDRcp/PICADD pairs. In PIC mode, the constant pool
+; need a label to do address computation. This label is emitted when backend emits
+; PICADD. When the target becomes dead, PICADD will be deleted. without this patch
+; LDRcp is dead but not being deleted. This will cause a dead contant pool entry
+; using a non existing label. This will cause an error in MC object emitting pass.
+
+; RUN: llc -relocation-model=pic -mcpu=cortex-a53 %s -filetype=obj -o - | llvm-nm - | FileCheck %s
+
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "armv8-unknown-linux-android"
+
+ at _ZN15UsecaseSelector25AllowedImplDefinedFormatsE = external dso_local unnamed_addr constant <{ i32, i32, i32, i32, [12 x i32] }>, align 4
+
+; Function Attrs: noinline nounwind optnone sspstrong uwtable
+define dso_local fastcc void @_ZN15UsecaseSelector26IsAllowedImplDefinedFormatE15ChiBufferFormatj() unnamed_addr #1 align 2 {
+  br label %1
+
+; <label>:1:                                      ; preds = %13, %0
+  %2 = icmp ult i32 undef, 4
+  br i1 %2, label %3, label %14
+
+; <label>:3:                                      ; preds = %1
+  br i1 undef, label %4, label %13
+
+; <label>:4:                                      ; preds = %3
+  %5 = getelementptr inbounds [16 x i32], [16 x i32]* bitcast (<{ i32, i32, i32, i32, [12 x i32] }>* @_ZN15UsecaseSelector25AllowedImplDefinedFormatsE to [16 x i32]*), i32 0, i32 undef
+  %6 = load i32, i32* %5, align 4
+  %7 = icmp eq i32 10, %6
+  br i1 %7, label %9, label %8
+
+; <label>:8:                                      ; preds = %4
+  br i1 undef, label %9, label %12
+
+; <label>:9:                                      ; preds = %8, %4
+  br i1 undef, label %10, label %13
+
+; <label>:10:                                     ; preds = %9
+  br i1 undef, label %11, label %13
+
+; <label>:11:                                     ; preds = %10
+  br label %14
+
+; <label>:12:                                     ; preds = %8
+  br label %14
+
+; <label>:13:                                     ; preds = %10, %9, %3
+  br label %1
+
+; <label>:14:                                     ; preds = %12, %11, %1
+  ret void
+}
+
+attributes #1 = { noinline optnone }
+
+; CHECK: _ZN15UsecaseSelector26IsAllowedImplDefinedFormatE15ChiBufferFormatj
+
Index: llvm/trunk/lib/Target/ARM/ARMFastISel.cpp
===================================================================
--- llvm/trunk/lib/Target/ARM/ARMFastISel.cpp
+++ llvm/trunk/lib/Target/ARM/ARMFastISel.cpp
@@ -2970,12 +2970,16 @@
   unsigned ConstAlign =
       MF->getDataLayout().getPrefTypeAlignment(Type::getInt32PtrTy(*Context));
   unsigned Idx = MF->getConstantPool()->getConstantPoolIndex(CPV, ConstAlign);
+  MachineMemOperand *CPMMO =
+      MF->getMachineMemOperand(MachinePointerInfo::getConstantPool(*MF),
+                               MachineMemOperand::MOLoad, 4, 4);
 
   unsigned TempReg = MF->getRegInfo().createVirtualRegister(&ARM::rGPRRegClass);
   unsigned Opc = isThumb2 ? ARM::t2LDRpci : ARM::LDRcp;
   MachineInstrBuilder MIB =
       BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(Opc), TempReg)
-          .addConstantPoolIndex(Idx);
+          .addConstantPoolIndex(Idx)
+          .addMemOperand(CPMMO);
   if (Opc == ARM::LDRcp)
     MIB.addImm(0);
   MIB.add(predOps(ARMCC::AL));
@@ -2988,6 +2992,7 @@
   MIB = BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(Opc), DestReg)
             .addReg(TempReg)
             .addImm(ARMPCLabelIndex);
+
   if (!Subtarget->isThumb())
     MIB.add(predOps(ARMCC::AL));
 


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