New llc option pie-copy-relocations to optimize access to extern globals.
This option indicates copy relocations support is available from the linker
when building as PIE and allows accesses to extern globals to avoid the GOT.
Differential Revision: https://reviews.llvm.org/D24849
llvm-svn: 284160
diff --git a/llvm/test/CodeGen/X86/global-access-pie-copyrelocs.ll b/llvm/test/CodeGen/X86/global-access-pie-copyrelocs.ll
new file mode 100644
index 0000000..5c4a87c
--- /dev/null
+++ b/llvm/test/CodeGen/X86/global-access-pie-copyrelocs.ll
@@ -0,0 +1,119 @@
+; RUN: llc < %s -march=x86-64 -mcpu=generic -mtriple=x86_64-linux-gnu -relocation-model=pic -pie-copy-relocations \
+; RUN: | FileCheck -check-prefix=X64 %s
+; RUN: llc < %s -emulated-tls -march=x86 -mcpu=generic -mtriple=i386-linux-gnu -relocation-model=pic -pie-copy-relocations \
+; 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@GOTOFF(%eax), %eax
+; X64-LABEL: my_access_global_load_d:
+; X64: movl d(%rip), %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 $2, d@GOTOFF(%eax)
+; X64-LABEL: my_access_global_store_d:
+; X64: movl $2, d(%rip)
+
+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
+}
+
+!llvm.module.flags = !{!0, !1}
+!0 = !{i32 1, !"PIC Level", i32 1}
+!1 = !{i32 1, !"PIE Level", i32 1}