Differential Revision: http://reviews.llvm.org/D19040

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@267229 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/X86Subtarget.cpp

@@ -83,8 +83,12 @@ ClassifyGlobalReference(const GlobalValue *GV, const TargetMachine &TM) const {
     } else if (!isTargetWin64()) {
       assert(isTargetELF() && "Unknown rip-relative target");
 
-      // Extra load is needed for all externally visible globals.
-      if (!GV->hasLocalLinkage() && GV->hasDefaultVisibility())
+      // Extra load is needed for all externally visible globals except with
+      // PIE as the definition of the global in an executable is not
+      // overridden.
+
+      if (!GV->hasLocalLinkage() && GV->hasDefaultVisibility() &&
+          !isGlobalDefinedInPIE(GV, TM))
         return X86II::MO_GOTPCREL;
     }
 
@@ -92,8 +96,11 @@ ClassifyGlobalReference(const GlobalValue *GV, const TargetMachine &TM) const {
   }
 
   if (isPICStyleGOT()) {   // 32-bit ELF targets.
-    // Extra load is needed for all externally visible.
-    if (GV->hasLocalLinkage() || GV->hasHiddenVisibility())
+    // Extra load is needed for all externally visible globals except with
+    // PIE as the definition of the global in an executable is not overridden.
+
+    if (GV->hasLocalLinkage() || GV->hasHiddenVisibility() ||
+        isGlobalDefinedInPIE(GV, TM))
       return X86II::MO_GOTOFF;
     return X86II::MO_GOT;
   }

lib/Target/X86/X86Subtarget.h

@@ -548,6 +548,14 @@ public:
     }
   }
 
+  /// Determine if this global is defined in a Position Independent
+  /// Executable (PIE) where its definition cannot be interposed.
+  bool isGlobalDefinedInPIE(const GlobalValue *GV,
+                            const TargetMachine &TM) const {
+    return TM.Options.PositionIndependentExecutable &&
+           !GV->isDeclarationForLinker();
+  }
+
   /// ClassifyGlobalReference - Classify a global variable reference for the
   /// current subtarget according to how we should reference it in a non-pcrel
   /// context.

test/CodeGen/X86/emutls-pie.ll

@@ -39,7 +39,7 @@ entry:
 
 define i32 @f1() {
 ; X32-LABEL: f1:
-; X32:      movl __emutls_v.i@GOT(%ebx), %eax
+; X32:      leal __emutls_v.i@GOTOFF(%ebx), %eax
 ; X32-NEXT: movl %eax, (%esp)
 ; X32-NEXT: calll __emutls_get_address@PLT
 ; X32-NEXT: movl (%eax), %eax
@@ -47,7 +47,7 @@ define i32 @f1() {
 ; X32-NEXT: popl %ebx
 ; X32-NEXT: retl
 ; X64-LABEL: f1:
-; X64:      movq __emutls_v.i@GOTPCREL(%rip), %rdi
+; X64:      leaq __emutls_v.i(%rip), %rdi
 ; X64-NEXT: callq __emutls_get_address@PLT
 ; X64-NEXT: movl (%rax), %eax
 ; X64-NEXT: popq %rcx
@@ -60,11 +60,11 @@ entry:
 
 define i32* @f2() {
 ; X32-LABEL: f2:
-; X32:      movl __emutls_v.i@GOT(%ebx), %eax
+; X32:      leal __emutls_v.i@GOTOFF(%ebx), %eax
 ; X32-NEXT: movl %eax, (%esp)
 ; X32-NEXT: calll __emutls_get_address@PLT
 ; X64-LABEL: f2:
-; X64:      movq __emutls_v.i@GOTPCREL(%rip), %rdi
+; X64:      leaq __emutls_v.i(%rip), %rdi
 ; X64-NEXT: callq __emutls_get_address@PLT
 
 entry:

test/CodeGen/X86/global-access-pie.ll

@@ -0,0 +1,119 @@
+; RUN: llc < %s -march=x86-64 -mcpu=generic -mtriple=x86_64-linux-gnu -relocation-model=pic -enable-pie \
+; RUN:   | FileCheck -check-prefix=X64 %s
+; RUN: llc < %s -emulated-tls -march=x86 -mcpu=generic -mtriple=i386-linux-gnu -relocation-model=pic -enable-pie \
+; RUN:   | FileCheck -check-prefix=X32 %s
+
+; External Linkage
+@a = global i32 0, align 4
+
+define i32 @my_access_global_a() #0 {
+; X32-LABEL: my_access_global_a:
+; X32:       addl $_GLOBAL_OFFSET_TABLE_{{.*}}, %eax
+; X32-NEXT:  movl a@GOTOFF(%eax), %eax
+; X64-LABEL: my_access_global_a:
+; X64:       movl a(%rip), %eax
+
+entry:
+  %0 = load i32, i32* @a, align 4
+  ret i32 %0
+}
+
+; WeakAny Linkage
+@b = weak global i32 0, align 4
+
+define i32 @my_access_global_b() #0 {
+; X32-LABEL: my_access_global_b:
+; X32:       addl $_GLOBAL_OFFSET_TABLE_{{.*}}, %eax
+; X32-NEXT:  movl b@GOTOFF(%eax), %eax
+; X64-LABEL: my_access_global_b:
+; X64:       movl b(%rip), %eax
+
+entry:
+  %0 = load i32, i32* @b, align 4
+  ret i32 %0
+}
+
+; Internal Linkage
+@c = internal global i32 0, align 4
+
+define i32 @my_access_global_c() #0 {
+; X32-LABEL: my_access_global_c:
+; X32:       addl $_GLOBAL_OFFSET_TABLE_{{.*}}, %eax
+; X32-NEXT:  movl c@GOTOFF(%eax), %eax
+; X64-LABEL: my_access_global_c:
+; X64:       movl c(%rip), %eax
+
+entry:
+  %0 = load i32, i32* @c, align 4
+  ret i32 %0
+}
+
+; External Linkage, only declaration.
+@d = external global i32, align 4
+
+define i32 @my_access_global_load_d() #0 {
+; X32-LABEL: my_access_global_load_d:
+; X32:       addl $_GLOBAL_OFFSET_TABLE_{{.*}}, %eax
+; X32-NEXT:  movl d@GOT(%eax), %eax
+; X32-NEXT:  movl (%eax), %eax
+; X64-LABEL: my_access_global_load_d:
+; X64:       movq d@GOTPCREL(%rip), %rax
+; X64-NEXT:  movl (%rax), %eax
+
+entry:
+  %0 = load i32, i32* @d, align 4
+  ret i32 %0
+}
+
+; External Linkage, only declaration, store a value.
+
+define i32 @my_access_global_store_d() #0 {
+; X32-LABEL: my_access_global_store_d:
+; X32:       addl $_GLOBAL_OFFSET_TABLE_{{.*}}, %eax
+; X32-NEXT:  movl d@GOT(%eax), %eax
+; X32-NEXT:  movl $2, (%eax)
+; X64-LABEL: my_access_global_store_d:
+; X64:       movq d@GOTPCREL(%rip), %rax
+; X64-NEXT:  movl $2, (%rax)
+
+entry:
+  store i32 2, i32* @d, align 4
+  ret i32 0
+}
+
+; External Linkage, function pointer access.
+declare i32 @access_fp(i32 ()*)
+declare i32 @foo()
+
+define i32 @my_access_fp_foo() #0 {
+; X32-LABEL: my_access_fp_foo:
+; X32:       addl $_GLOBAL_OFFSET_TABLE_{{.*}}, %ebx
+; X32-NEXT:  movl	foo@GOT(%ebx), %eax
+; X64-LABEL: my_access_fp_foo:
+; X64:       movq foo@GOTPCREL(%rip), %rdi
+
+entry:
+  %call = call i32 @access_fp(i32 ()* @foo)
+  ret i32 %call
+}
+
+; LinkOnceODR Linkage, function pointer access.
+
+$bar = comdat any
+
+define linkonce_odr i32 @bar() comdat {
+entry:
+  ret i32 0
+}
+
+define i32 @my_access_fp_bar() #0 {
+; X32-LABEL: my_access_fp_bar:
+; X32:       addl $_GLOBAL_OFFSET_TABLE_{{.*}}, %ebx
+; X32-NEXT:  leal	bar@GOTOFF(%ebx), %eax
+; X64-LABEL: my_access_fp_bar:
+; X64:       leaq bar(%rip), %rdi
+
+entry:
+  %call = call i32 @access_fp(i32 ()* @bar)
+  ret i32 %call
+}