[llvm] r338651 - Load from the GOT for external symbols in the large, PIC code model

Wed Aug 1 15:56:05 PDT 2018

Author: rnk
Date: Wed Aug  1 15:56:05 2018
New Revision: 338651

URL: http://llvm.org/viewvc/llvm-project?rev=338651&view=rev
Log:
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

Added:
    llvm/trunk/test/CodeGen/X86/code-model-elf-memset.ll
Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=338651&r1=338650&r2=338651&view=diff
==============================================================================

--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Wed Aug  1 15:56:05 2018
@@ -15793,7 +15793,7 @@ X86TargetLowering::LowerExternalSymbol(S
   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);

Added: llvm/trunk/test/CodeGen/X86/code-model-elf-memset.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/code-model-elf-memset.ll?rev=338651&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/code-model-elf-memset.ll (added)
+++ llvm/trunk/test/CodeGen/X86/code-model-elf-memset.ll Wed Aug  1 15:56:05 2018
@@ -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 at 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 at 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 at 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 "}


