From 886a8633738d5e23c39d513b5383a3038645dddc Mon Sep 17 00:00:00 2001
From: Reid Kleckner <rnk@google.com>
Date: Wed, 1 Aug 2018 22:56:05 +0000
Subject: [PATCH] Load from the GOT for external symbols in the large, PIC code
 model

Do the same handling for external symbols that we do for jump table
symbols and global values.

Fixes one of the cases in PR38385

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@338651 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/X86/X86ISelLowering.cpp        |  2 +-
 test/CodeGen/X86/code-model-elf-memset.ll | 91 +++++++++++++++++++++++++++++++
 2 files changed, 92 insertions(+), 1 deletion(-)
 create mode 100644 test/CodeGen/X86/code-model-elf-memset.ll

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index f77a716434f..660255612ee 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -15793,7 +15793,7 @@ X86TargetLowering::LowerExternalSymbol(SDValue Op, SelectionDAG &DAG) const {
   Result = DAG.getNode(getGlobalWrapperKind(), DL, PtrVT, Result);
 
   // With PIC, the address is actually $g + Offset.
-  if (isPositionIndependent() && !Subtarget.is64Bit()) {
+  if (OpFlag) {
     Result =
         DAG.getNode(ISD::ADD, DL, PtrVT,
                     DAG.getNode(X86ISD::GlobalBaseReg, SDLoc(), PtrVT), Result);
diff --git a/test/CodeGen/X86/code-model-elf-memset.ll b/test/CodeGen/X86/code-model-elf-memset.ll
new file mode 100644
index 00000000000..ba34aaeddcb
--- /dev/null
+++ b/test/CodeGen/X86/code-model-elf-memset.ll
@@ -0,0 +1,91 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; Run with --no_x86_scrub_rip because we care a lot about how globals are
+; accessed in the code model.
+
+; Memset is interesting because it is an ExternalSymbol reference instead of a
+; GlobalValue. Make sure we do the right GOT load for 64-bit large.
+
+; RUN: llc < %s -relocation-model=pic    -code-model=small  | FileCheck %s --check-prefix=CHECK --check-prefix=SMALL-PIC
+; RUN: llc < %s -relocation-model=pic    -code-model=medium | FileCheck %s --check-prefix=CHECK --check-prefix=MEDIUM-PIC
+; RUN: llc < %s -relocation-model=pic    -code-model=large  | FileCheck %s --check-prefix=CHECK --check-prefix=LARGE-PIC
+
+; Generated from this C source:
+;
+; int main() {
+;   unsigned int a[100] = {0};
+;   return 0;
+; }
+
+; ModuleID = 'model.c'
+source_filename = "model.c"
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64--linux"
+
+declare void @llvm.memset.p0i8.i64(i8* nocapture writeonly, i8, i64, i1) #1
+
+define i32 @main() #0 {
+; SMALL-PIC-LABEL: main:
+; SMALL-PIC:       # %bb.0: # %entry
+; SMALL-PIC-NEXT:    subq $424, %rsp # imm = 0x1A8
+; SMALL-PIC-NEXT:    .cfi_def_cfa_offset 432
+; SMALL-PIC-NEXT:    movl $0, {{[0-9]+}}(%rsp)
+; SMALL-PIC-NEXT:    leaq {{[0-9]+}}(%rsp), %rdi
+; SMALL-PIC-NEXT:    xorl %esi, %esi
+; SMALL-PIC-NEXT:    movl $400, %edx # imm = 0x190
+; SMALL-PIC-NEXT:    callq memset@PLT
+; SMALL-PIC-NEXT:    xorl %eax, %eax
+; SMALL-PIC-NEXT:    addq $424, %rsp # imm = 0x1A8
+; SMALL-PIC-NEXT:    .cfi_def_cfa_offset 8
+; SMALL-PIC-NEXT:    retq
+;
+; MEDIUM-PIC-LABEL: main:
+; MEDIUM-PIC:       # %bb.0: # %entry
+; MEDIUM-PIC-NEXT:    subq $424, %rsp # imm = 0x1A8
+; MEDIUM-PIC-NEXT:    .cfi_def_cfa_offset 432
+; MEDIUM-PIC-NEXT:    movl $0, {{[0-9]+}}(%rsp)
+; MEDIUM-PIC-NEXT:    leaq {{[0-9]+}}(%rsp), %rdi
+; MEDIUM-PIC-NEXT:    xorl %esi, %esi
+; MEDIUM-PIC-NEXT:    movl $400, %edx # imm = 0x190
+; MEDIUM-PIC-NEXT:    callq memset@PLT
+; MEDIUM-PIC-NEXT:    xorl %eax, %eax
+; MEDIUM-PIC-NEXT:    addq $424, %rsp # imm = 0x1A8
+; MEDIUM-PIC-NEXT:    .cfi_def_cfa_offset 8
+; MEDIUM-PIC-NEXT:    retq
+;
+; LARGE-PIC-LABEL: main:
+; LARGE-PIC:       # %bb.0: # %entry
+; LARGE-PIC-NEXT:    subq $424, %rsp # imm = 0x1A8
+; LARGE-PIC-NEXT:    .cfi_def_cfa_offset 432
+; LARGE-PIC-NEXT:  .Ltmp0:
+; LARGE-PIC-NEXT:    leaq {{.*}}(%rip), %rax
+; LARGE-PIC-NEXT:    movabsq $_GLOBAL_OFFSET_TABLE_-.Ltmp0, %rcx
+; LARGE-PIC-NEXT:    addq %rcx, %rax
+; LARGE-PIC-NEXT:    movl $0, {{[0-9]+}}(%rsp)
+; LARGE-PIC-NEXT:    leaq {{[0-9]+}}(%rsp), %rdi
+; LARGE-PIC-NEXT:    movabsq $memset@GOT, %rcx
+; LARGE-PIC-NEXT:    xorl %esi, %esi
+; LARGE-PIC-NEXT:    movl $400, %edx # imm = 0x190
+; LARGE-PIC-NEXT:    callq *(%rax,%rcx)
+; LARGE-PIC-NEXT:    xorl %eax, %eax
+; LARGE-PIC-NEXT:    addq $424, %rsp # imm = 0x1A8
+; LARGE-PIC-NEXT:    .cfi_def_cfa_offset 8
+; LARGE-PIC-NEXT:    retq
+entry:
+  %retval = alloca i32, align 4
+  %a = alloca [100 x i32], align 16
+  store i32 0, i32* %retval, align 4
+  %0 = bitcast [100 x i32]* %a to i8*
+  call void @llvm.memset.p0i8.i64(i8* align 16 %0, i8 0, i64 400, i1 false)
+  ret i32 0
+}
+
+attributes #0 = { noinline nounwind uwtable }
+attributes #0 = { argmemonly nounwind uwtable }
+
+!llvm.module.flags = !{!0, !1, !2}
+!llvm.ident = !{!3}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 7, !"PIC Level", i32 2}
+!2 = !{i32 7, !"PIE Level", i32 2}
+!3 = !{!"clang version 7.0.0 "}
-- 
2.11.0