From ffd0b31c7cbaa8322d2963afe6ace4e3a0889ddb Mon Sep 17 00:00:00 2001
From: David Green <david.green@arm.com>
Date: Tue, 1 Sep 2020 07:39:54 +0100
Subject: [PATCH] Revert "[ARM] Register pressure with -mthumb forces register
 reload before each call"

Expensive checks are failing, complaining about additional MMO operands
added to the branch.
---
 llvm/lib/Target/ARM/Thumb1InstrInfo.cpp     | 34 ---------------------
 llvm/lib/Target/ARM/Thumb1InstrInfo.h       |  7 -----
 llvm/test/CodeGen/ARM/minsize-call-cse-2.ll | 20 ------------
 llvm/test/CodeGen/ARM/minsize-call-cse-3.ll | 16 ----------
 4 files changed, 77 deletions(-)
 delete mode 100644 llvm/test/CodeGen/ARM/minsize-call-cse-2.ll
 delete mode 100644 llvm/test/CodeGen/ARM/minsize-call-cse-3.ll

diff --git a/llvm/lib/Target/ARM/Thumb1InstrInfo.cpp b/llvm/lib/Target/ARM/Thumb1InstrInfo.cpp
index 7eec05df88ca..79afa378cb62 100644
--- a/llvm/lib/Target/ARM/Thumb1InstrInfo.cpp
+++ b/llvm/lib/Target/ARM/Thumb1InstrInfo.cpp
@@ -152,37 +152,3 @@ bool Thumb1InstrInfo::canCopyGluedNodeDuringSchedule(SDNode *N) const {
 
   return false;
 }
-
-MachineInstr *Thumb1InstrInfo::foldMemoryOperandImpl(
-    MachineFunction &MF, MachineInstr &MI, ArrayRef<unsigned> Ops,
-    MachineBasicBlock::iterator InsertPt, MachineInstr &LoadMI,
-    LiveIntervals *LIS) const {
-  // Replace:
-  // ldr Rd, func address
-  // blx Rd
-  // with:
-  // bl func
-
-  if (MI.getOpcode() == ARM::tBLXr && LoadMI.getOpcode() == ARM::tLDRpci &&
-      MI.getParent() == LoadMI.getParent()) {
-    unsigned CPI = LoadMI.getOperand(1).getIndex();
-    const MachineConstantPool *MCP = MF.getConstantPool();
-    if (CPI >= MCP->getConstants().size())
-      return nullptr;
-    const MachineConstantPoolEntry &CPE = MCP->getConstants()[CPI];
-    assert(!CPE.isMachineConstantPoolEntry() && "Invalid constpool entry");
-    const Function *Callee = dyn_cast<Function>(CPE.Val.ConstVal);
-    if (!Callee)
-      return nullptr;
-    const char *FuncName = MF.createExternalSymbolName(Callee->getName());
-    MachineInstrBuilder MIB =
-        BuildMI(*MI.getParent(), InsertPt, MI.getDebugLoc(), get(ARM::tBL))
-            .add(predOps(ARMCC::AL))
-            .addExternalSymbol(FuncName);
-    for (auto &MO : MI.implicit_operands())
-      MIB.add(MO);
-    return MIB.getInstr();
-  }
-
-  return nullptr;
-}
diff --git a/llvm/lib/Target/ARM/Thumb1InstrInfo.h b/llvm/lib/Target/ARM/Thumb1InstrInfo.h
index bc4da451ca5d..017b7222337c 100644
--- a/llvm/lib/Target/ARM/Thumb1InstrInfo.h
+++ b/llvm/lib/Target/ARM/Thumb1InstrInfo.h
@@ -53,13 +53,6 @@ public:
                             const TargetRegisterInfo *TRI) const override;
 
   bool canCopyGluedNodeDuringSchedule(SDNode *N) const override;
-
-protected:
-  virtual MachineInstr *foldMemoryOperandImpl(
-      MachineFunction &MF, MachineInstr &MI, ArrayRef<unsigned> Ops,
-      MachineBasicBlock::iterator InsertPt, MachineInstr &LoadMI,
-      LiveIntervals *LIS = nullptr) const override;
-
 private:
   void expandLoadStackGuard(MachineBasicBlock::iterator MI) const override;
 };
diff --git a/llvm/test/CodeGen/ARM/minsize-call-cse-2.ll b/llvm/test/CodeGen/ARM/minsize-call-cse-2.ll
deleted file mode 100644
index 4f9e508c1c97..000000000000
--- a/llvm/test/CodeGen/ARM/minsize-call-cse-2.ll
+++ /dev/null
@@ -1,20 +0,0 @@
-; RUN: llc < %s | FileCheck %s
-
-target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
-target triple = "thumbv6m-arm-none-eabi"
-
-; CHECK-LABEL: f:
-; CHECK: bl g
-; CHECK: blx r
-; CHECK: bl g
-; CHECK: bl g
-define void @f(i32* %p, i32 %x, i32 %y, i32 %z) minsize optsize {
-entry:
-  call void @g(i32* %p, i32 %x, i32 %y, i32 %z)
-  call void @g(i32* %p, i32 %x, i32 %y, i32 %z)
-  call void @g(i32* %p, i32 %x, i32 %y, i32 %z)
-  call void @g(i32* %p, i32 %x, i32 %y, i32 %z)
-  ret void
-}
-
-declare void @g(i32*,i32,i32,i32)
diff --git a/llvm/test/CodeGen/ARM/minsize-call-cse-3.ll b/llvm/test/CodeGen/ARM/minsize-call-cse-3.ll
deleted file mode 100644
index abe1f0347e5d..000000000000
--- a/llvm/test/CodeGen/ARM/minsize-call-cse-3.ll
+++ /dev/null
@@ -1,16 +0,0 @@
-; RUN: llc < %s
-; Verify that we don't crash on indirect function calls
-; in Thumb1InstrInfo::foldMemoryOperand.
-
-target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
-target triple = "thumbv6m-arm-none-eabi"
-
-; Function Attrs: minsize nounwind optsize
-define void @test(i32* %p, i32 %x, i32 %y, i32 %z) {
-entry:
-  tail call void inttoptr (i32 19088743 to void (i32*, i32, i32, i32)*)(i32* %p, i32 %x, i32 %y, i32 %z)
-  tail call void inttoptr (i32 19088743 to void (i32*, i32, i32, i32)*)(i32* %p, i32 %x, i32 %y, i32 %z)
-  tail call void inttoptr (i32 19088743 to void (i32*, i32, i32, i32)*)(i32* %p, i32 %x, i32 %y, i32 %z)
-  tail call void inttoptr (i32 19088743 to void (i32*, i32, i32, i32)*)(i32* %p, i32 %x, i32 %y, i32 %z)
-  ret void
-}