Recommit r335333 "[MC] - Add .stack_size sections into groups and link them with .text"

With compilation fix.

Original commit message:

D39788 added a '.stack-size' section containing metadata on function stack sizes
to output ELF files behind the new -stack-size-section flag.

This change does following two things on top:

1) Imagine the case when there are -ffunction-sections flag given and there are text sections in COMDATs. 
    The patch adds a '.stack-size' section into corresponding COMDAT group, so that linker will be able to
    eliminate them fast during resolving the COMDATs.
2) Patch sets a SHF_LINK_ORDER flag and links '.stack-size' with the corresponding .text.
   With that linker will be able to do -gc-sections on dead stack sizes sections.

Differential revision: https://reviews.llvm.org/D46874

llvm-svn: 335336

1 files changed, 19 insertions, 2 deletions

diff --git a/llvm/test/CodeGen/X86/stack-size-section.ll b/llvm/test/CodeGen/X86/stack-size-section.ll
index 80fa2ccf6cc..7e7ba5b9d4e 100644
--- a/llvm/test/CodeGen/X86/stack-size-section.ll
+++ b/llvm/test/CodeGen/X86/stack-size-section.ll
@@ -2,7 +2,7 @@
 
 ; CHECK-LABEL: func1:
 ; CHECK-NEXT: .Lfunc_begin0:
-; CHECK: .section .stack_sizes,"",@progbits
+; CHECK: .section .stack_sizes,"o",@progbits
 ; CHECK-NEXT: .quad .Lfunc_begin0
 ; CHECK-NEXT: .byte 8
 define void @func1(i32, i32) #0 {
@@ -13,7 +13,7 @@ define void @func1(i32, i32) #0 {
 
 ; CHECK-LABEL: func2:
 ; CHECK-NEXT: .Lfunc_begin1:
-; CHECK: .section .stack_sizes,"",@progbits
+; CHECK: .section .stack_sizes,"o",@progbits
 ; CHECK-NEXT: .quad .Lfunc_begin1
 ; CHECK-NEXT: .byte 24
 define void @func2() #0 {
@@ -22,6 +22,23 @@ define void @func2() #0 {
   ret void
 }
 
+; Check that we still put .stack_sizes into the corresponding COMDAT group if any.
+; CHECK: .section .text._Z4fooTIiET_v,"axG",@progbits,_Z4fooTIiET_v,comdat
+; CHECK: .section .stack_sizes,"Go",@progbits,_Z4fooTIiET_v,comdat,.text._Z4fooTIiET_v,unique,1
+$_Z4fooTIiET_v = comdat any
+define linkonce_odr dso_local i32 @_Z4fooTIiET_v() comdat {
+  ret i32 0
+}
+
+; Check that we assign a unique ID to .stack_sizes if it is linked with a unique .text section.
+; CHECK: .section .text.func3,"ax",@progbits
+; CHECK: .section .stack_sizes,"o",@progbits,.text.func3,unique,2
+define dso_local i32 @func3() section ".text.func3" {
+  %1 = alloca i32, align 4
+  store i32 0, i32* %1, align 4
+  ret i32 0
+}
+
 ; CHECK-LABEL: dynalloc:
 ; CHECK-NOT: .section .stack_sizes
 define void @dynalloc(i32 %N) #0 {