From d6412c940ef863d02595f7be094d8cd3afc908a1 Mon Sep 17 00:00:00 2001
From: Eli Friedman <eli.friedman@gmail.com>
Date: Fri, 3 Jun 2011 01:13:19 +0000
Subject: [PATCH] Add ARM fast-isel support for materializing the address of a
 global in cases where the global uses an indirect symbol.

rdar://9431157



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132522 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/ARMFastISel.cpp | 20 +++++++++++++++++---
 test/CodeGen/ARM/fast-isel.ll  | 28 +++++++++++++++++++++++++++-
 2 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/lib/Target/ARM/ARMFastISel.cpp b/lib/Target/ARM/ARMFastISel.cpp
index ed9586897a8..bcfa5c55eba 100644
--- a/lib/Target/ARM/ARMFastISel.cpp
+++ b/lib/Target/ARM/ARMFastISel.cpp
@@ -577,9 +577,6 @@ unsigned ARMFastISel::ARMMaterializeGV(const GlobalValue *GV, EVT VT) {
 
   Reloc::Model RelocM = TM.getRelocationModel();
 
-  // TODO: No external globals for now.
-  if (Subtarget->GVIsIndirectSymbol(GV, RelocM)) return 0;
-
   // TODO: Need more magic for ARM PIC.
   if (!isThumb && (RelocM == Reloc::PIC_)) return 0;
 
@@ -614,6 +611,23 @@ unsigned ARMFastISel::ARMMaterializeGV(const GlobalValue *GV, EVT VT) {
           .addImm(0);
   }
   AddOptionalDefs(MIB);
+
+  if (Subtarget->GVIsIndirectSymbol(GV, RelocM)) {
+    unsigned NewDestReg = createResultReg(TLI.getRegClassFor(VT));
+    if (isThumb)
+      MIB = BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, TII.get(ARM::t2LDRi12),
+                    NewDestReg)
+            .addReg(DestReg)
+            .addImm(0);
+    else
+      MIB = BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, TII.get(ARM::LDRi12),
+                    NewDestReg)
+            .addReg(DestReg)
+            .addImm(0);
+    DestReg = NewDestReg;
+    AddOptionalDefs(MIB);
+  }
+
   return DestReg;
 }
 
diff --git a/test/CodeGen/ARM/fast-isel.ll b/test/CodeGen/ARM/fast-isel.ll
index 8299c81078c..499c97fe53c 100644
--- a/test/CodeGen/ARM/fast-isel.ll
+++ b/test/CodeGen/ARM/fast-isel.ll
@@ -131,4 +131,30 @@ bb3:
 ; ARM: sxth
 ; ARM: add
 ; ARM: sub
-}
\ No newline at end of file
+}
+
+; Check loads/stores with globals
+@test4g = external global i32
+
+define void @test4() {
+  %a = load i32* @test4g
+  %b = add i32 %a, 1
+  store i32 %b, i32* @test4g
+  ret void
+
+; THUMB: ldr.n r0, LCPI4_1
+; THUMB: ldr r0, [r0]
+; THUMB: ldr r0, [r0]
+; THUMB: adds r0, #1
+; THUMB: ldr.n r1, LCPI4_0
+; THUMB: ldr r1, [r1]
+; THUMB: str r0, [r1]
+
+; ARM: ldr r0, LCPI4_1
+; ARM: ldr r0, [r0]
+; ARM: ldr r0, [r0]
+; ARM: add r0, r0, #1
+; ARM: ldr r1, LCPI4_0
+; ARM: ldr r1, [r1]
+; ARM: str r0, [r1]
+}