From 1437f6d710ecf2c7a6aa19858e57a93ee0685338 Mon Sep 17 00:00:00 2001
From: Diana Picus <diana.picus@linaro.org>
Date: Mon, 19 Dec 2016 11:55:41 +0000
Subject: [PATCH] [ARM] GlobalISel: Lower more than 4 arguments

This adds support for lowering more than 4 arguments (although still i32 only).
It uses the handleAssignments / ValueHandler infrastructure extracted from
the AArch64 backend in r288658.

Differential Revision: https://reviews.llvm.org/D27195

llvm-svn: 290098
---
 llvm/lib/Target/ARM/ARMCallLowering.cpp       | 32 +++++++++++++------
 .../ARM/GlobalISel/arm-irtranslator.ll        | 17 ++++++++++
 llvm/test/CodeGen/ARM/GlobalISel/arm-isel.ll  | 11 +++++++
 3 files changed, 50 insertions(+), 10 deletions(-)

diff --git a/llvm/lib/Target/ARM/ARMCallLowering.cpp b/llvm/lib/Target/ARM/ARMCallLowering.cpp
index f266e1889505..de40dd0db0e2 100644
--- a/llvm/lib/Target/ARM/ARMCallLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMCallLowering.cpp
@@ -19,6 +19,7 @@
 #include "ARMISelLowering.h"
 
 #include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
 
 using namespace llvm;
 
@@ -115,7 +116,27 @@ struct FormalArgHandler : public CallLowering::ValueHandler {
 
   unsigned getStackAddress(uint64_t Size, int64_t Offset,
                            MachinePointerInfo &MPO) override {
-    llvm_unreachable("Don't know how to get a stack address yet");
+    assert(Size == 4 && "Unsupported size");
+
+    auto &MFI = MIRBuilder.getMF().getFrameInfo();
+
+    int FI = MFI.CreateFixedObject(Size, Offset, true);
+    MPO = MachinePointerInfo::getFixedStack(MIRBuilder.getMF(), FI);
+
+    unsigned AddrReg =
+        MRI.createGenericVirtualRegister(LLT::pointer(MPO.getAddrSpace(), 32));
+    MIRBuilder.buildFrameIndex(AddrReg, FI);
+
+    return AddrReg;
+  }
+
+  void assignValueToAddress(unsigned ValVReg, unsigned Addr, uint64_t Size,
+                            MachinePointerInfo &MPO, CCValAssign &VA) override {
+    assert(Size == 4 && "Unsupported size");
+
+    auto MMO = MIRBuilder.getMF().getMachineMemOperand(
+        MPO, MachineMemOperand::MOLoad, Size, /* Alignment */ 0);
+    MIRBuilder.buildLoad(ValVReg, Addr, *MMO);
   }
 
   void assignValueToReg(unsigned ValVReg, unsigned PhysReg,
@@ -129,11 +150,6 @@ struct FormalArgHandler : public CallLowering::ValueHandler {
     MIRBuilder.getMBB().addLiveIn(PhysReg);
     MIRBuilder.buildCopy(ValVReg, PhysReg);
   }
-
-  void assignValueToAddress(unsigned ValVReg, unsigned Addr, uint64_t Size,
-                            MachinePointerInfo &MPO, CCValAssign &VA) override {
-    llvm_unreachable("Don't know how to assign a value to an address yet");
-  }
 };
 } // End anonymous namespace
 
@@ -144,10 +160,6 @@ bool ARMCallLowering::lowerFormalArguments(MachineIRBuilder &MIRBuilder,
   if (F.arg_empty())
     return true;
 
-  // Stick to only 4 arguments for now
-  if (F.arg_size() > 4)
-    return false;
-
   if (F.isVarArg())
     return false;
 
diff --git a/llvm/test/CodeGen/ARM/GlobalISel/arm-irtranslator.ll b/llvm/test/CodeGen/ARM/GlobalISel/arm-irtranslator.ll
index de9e082d1ba5..a9909817bafd 100644
--- a/llvm/test/CodeGen/ARM/GlobalISel/arm-irtranslator.ll
+++ b/llvm/test/CodeGen/ARM/GlobalISel/arm-irtranslator.ll
@@ -19,3 +19,20 @@ entry:
   %sum = add i32 %x, %y
   ret i32 %sum
 }
+
+define i32 @test_many_args(i32 %p0, i32 %p1, i32 %p2, i32 %p3, i32 %p4, i32 %p5) {
+; CHECK-LABEL: name: test_many_args
+; CHECK: fixedStack:
+; CHECK-DAG: id: [[P4:[0-9]]]{{.*}}offset: 0{{.*}}size: 4
+; CHECK-DAG: id: [[P5:[0-9]]]{{.*}}offset: 4{{.*}}size: 4
+; CHECK: liveins: %r0, %r1, %r2, %r3
+; CHECK: [[VREGP2:%[0-9]+]]{{.*}} = COPY %r2
+; CHECK: [[FIP5:%[0-9]+]]{{.*}} = G_FRAME_INDEX %fixed-stack.[[P5]]
+; CHECK: [[VREGP5:%[0-9]+]]{{.*}} = G_LOAD [[FIP5]]
+; CHECK: [[SUM:%[0-9]+]]{{.*}} = G_ADD [[VREGP2]], [[VREGP5]]
+; CHECK: %r0 = COPY [[SUM]]
+; CHECK: BX_RET 14, _, implicit %r0
+entry:
+  %sum = add i32 %p2, %p5
+  ret i32 %sum
+}
diff --git a/llvm/test/CodeGen/ARM/GlobalISel/arm-isel.ll b/llvm/test/CodeGen/ARM/GlobalISel/arm-isel.ll
index 0d62c6f7bfa9..59c788892ce9 100644
--- a/llvm/test/CodeGen/ARM/GlobalISel/arm-isel.ll
+++ b/llvm/test/CodeGen/ARM/GlobalISel/arm-isel.ll
@@ -15,3 +15,14 @@ entry:
   %sum = add i32 %x, %y
   ret i32 %sum
 }
+
+define i32 @test_many_args(i32 %p0, i32 %p1, i32 %p2, i32 %p3, i32 %p4, i32 %p5) {
+; CHECK-LABEL: test_many_args:
+; CHECK: add [[P5ADDR:r[0-9]+]], sp, #4
+; CHECK: ldr [[P5:r[0-9]+]], {{.*}}[[P5ADDR]]
+; CHECK: add r0, r2, [[P5]]
+; CHECK: bx lr
+entry:
+  %sum = add i32 %p2, %p5
+  ret i32 %sum
+}