[AsmPrinter] Link .section_sizes to the correct section (llvm#135583)

AsmPrinter may switch the current section when e.g., emitting a jump
table for a switch. `.stack_sizes` should still be linked to the
function section. If the section is wrong, readelf emits a warning
"relocation symbol is not in the expected section".

Author: s-barannikov

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -1586,7 +1586,7 @@ void AsmPrinter::emitStackSizeSection(const MachineFunction &MF) {
     return;
 
   MCSection *StackSizeSection =
-      getObjFileLowering().getStackSizesSection(*getCurrentSection());
+      getObjFileLowering().getStackSizesSection(*MF.getSection());
   if (!StackSizeSection)
     return;
 

llvm/test/CodeGen/AArch64/stack-size-section.ll

@@ -0,0 +1,63 @@
+; RUN: llc -mtriple=aarch64 -aarch64-min-jump-table-entries=4 -stack-size-section %s -o - | FileCheck %s
+
+; CHECK-LABEL: .section .stack_sizes,"o",@progbits,.text{{$}}
+; CHECK-NEXT: .xword .Lfunc_begin0
+; CHECK-NEXT: .byte 0
+define void @empty() {
+  ret void
+}
+
+; CHECK-LABEL: .section .stack_sizes,"o",@progbits,.text{{$}}
+; CHECK-NEXT: .xword .Lfunc_begin1
+; CHECK-NEXT: .ascii "\200\001"
+define void @non_empty() #0 {
+  alloca [32 x i32]
+  ret void
+}
+
+; CHECK-LABEL: dynalloc:
+; CHECK-NOT: .section .stack_sizes
+define void @dynalloc(i32 %n) #0 {
+  alloca i32, i32 %n
+  ret void
+}
+
+; Check that .stack_sizes section is linked to the function's section (.text),
+; and not to the section containing the jump table (.rodata).
+; CHECK-LABEL: linked_section:
+; CHECK: .section .rodata,"a",@progbits
+; CHECK: .section .stack_sizes,"o",@progbits,.text
+; CHECK-NEXT: .xword .Lfunc_begin3
+; CHECK-NEXT: .ascii "\220\001"
+declare void @case0()
+declare void @case1()
+declare void @case2()
+declare void @case3()
+define void @linked_section(i32 %x) {
+  %arr = alloca [32 x i32]
+  switch i32 %x, label %sw.epilog [
+    i32 0, label %sw.bb0
+    i32 1, label %sw.bb1
+    i32 2, label %sw.bb2
+    i32 3, label %sw.bb3
+  ]
+
+sw.bb0:
+  call void @case0()
+  ret void
+
+sw.bb1:
+  call void @case1()
+  ret void
+
+sw.bb2:
+  call void @case2()
+  ret void
+
+sw.bb3:
+  call void @case3()
+  ret void
+
+sw.epilog:
+  ret void
+}

llvm/test/CodeGen/SystemZ/stack-size-section.ll

@@ -38,4 +38,34 @@ define void @dynalloc(i32 %N) #0 {
   ret void
 }
 
+; Check that .stack_sizes section is linked to the function's section (.text),
+; and not to the section containing the jump table (.rodata).
+; CHECK-LABEL: .section .stack_sizes,"o",@progbits,.text{{$}}
+; CHECK-NEXT: .quad .Lfunc_begin4
+; CHECK-NEXT: .ascii "\260!"
+define i32 @linked_section(i32 %x) {
+  %arr = alloca [1024 x i32]
+  switch i32 %x, label %sw.epilog [
+    i32 0, label %sw.bb0
+    i32 1, label %sw.bb1
+    i32 2, label %sw.bb2
+    i32 3, label %sw.bb3
+  ]
+
+sw.bb0:
+  ret i32 0
+
+sw.bb1:
+  ret i32 1
+
+sw.bb2:
+  ret i32 2
+
+sw.bb3:
+  ret i32 3
+
+sw.epilog:
+  ret i32 -1
+}
+
 attributes #0 = { "frame-pointer"="all" }