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

4 files changed, 50 insertions, 7 deletions

diff --git a/llvm/test/CodeGen/ARM/stack-size-section.ll b/llvm/test/CodeGen/ARM/stack-size-section.ll
index 142261a9f2c..10f156439e3 100644
--- a/llvm/test/CodeGen/ARM/stack-size-section.ll
+++ b/llvm/test/CodeGen/ARM/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,.text,unique,0
 ; CHECK-NEXT: .long .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,.text,unique,0
 ; CHECK-NEXT: .long .Lfunc_begin1
 ; CHECK-NEXT: .byte 16
 define void @func2() #0 {
diff --git a/llvm/test/CodeGen/SystemZ/stack-size-section.ll b/llvm/test/CodeGen/SystemZ/stack-size-section.ll
index f0e421f957f..6aacc705115 100644
--- a/llvm/test/CodeGen/SystemZ/stack-size-section.ll
+++ b/llvm/test/CodeGen/SystemZ/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,.text,unique,0
 ; CHECK-NEXT: .quad .Lfunc_begin0
 ; CHECK-NEXT: .byte 0
 define void @func1(i32, i32) #0 {
@@ -11,7 +11,7 @@ define void @func1(i32, i32) #0 {
 
 ; CHECK-LABEL: func2:
 ; CHECK-NEXT: .Lfunc_begin1:
-; CHECK: .section .stack_sizes,"",@progbits
+; CHECK: .section .stack_sizes,"o",@progbits,.text,unique,0
 ; CHECK-NEXT: .quad .Lfunc_begin1
 ; CHECK-NEXT: .ascii  "\250\001"
 define void @func2(i32, i32) #0 {
@@ -22,7 +22,7 @@ define void @func2(i32, i32) #0 {
 
 ; CHECK-LABEL: func3:
 ; CHECK-NEXT: .Lfunc_begin2:
-; CHECK: .section .stack_sizes,"",@progbits
+; CHECK: .section .stack_sizes,"o",@progbits,.text,unique,0
 ; CHECK-NEXT: .quad .Lfunc_begin2
 ; CHECK-NEXT: .ascii  "\250\001"
 define void @func3() #0 {
diff --git a/llvm/test/CodeGen/X86/stack-size-section-function-sections.ll b/llvm/test/CodeGen/X86/stack-size-section-function-sections.ll
new file mode 100644
index 00000000000..c352bfe032c
--- /dev/null
+++ b/llvm/test/CodeGen/X86/stack-size-section-function-sections.ll
@@ -0,0 +1,26 @@
+; RUN: llc < %s -mtriple=x86_64-linux -stack-size-section -function-sections | FileCheck %s
+
+; Check we add SHF_LINK_ORDER for .stack_sizes and link it with the corresponding .text sections.
+; CHECK: .section        .text._Z3barv,"ax",@progbits
+; CHECK: .section        .stack_sizes,"o",@progbits,.text._Z3barv,unique,0
+; CHECK: .section        .text._Z3foov,"ax",@progbits
+; CHECK: .section        .stack_sizes,"o",@progbits,.text._Z3foov,unique,1
+
+; Check we add .stack_size section to a COMDAT group with the corresponding .text section if such a COMDAT exists.
+; CHECK: .section        .text._Z4fooTIiET_v,"axG",@progbits,_Z4fooTIiET_v,comdat
+; CHECK: .section        .stack_sizes,"Go",@progbits,_Z4fooTIiET_v,comdat,.text._Z4fooTIiET_v,unique,2
+
+$_Z4fooTIiET_v = comdat any
+
+define dso_local i32 @_Z3barv() {
+  ret i32 0
+}
+
+define dso_local i32 @_Z3foov() {
+  %1 = call i32 @_Z4fooTIiET_v()
+  ret i32 %1
+}
+
+define linkonce_odr dso_local i32 @_Z4fooTIiET_v() comdat {
+  ret i32 0
+}
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 {