[X86][test] Add tests for -fpatchable-function-entry=N,M (where M>0) …

…and its interaction with -fcf-protection=branch

Reviewed By: nickdesaulniers

Differential Revision: https://reviews.llvm.org/D73071

llvm/test/CodeGen/X86/patchable-function-entry-ibt.ll

@@ -0,0 +1,48 @@
+; RUN: llc -mtriple=x86_64 %s -o - | FileCheck --check-prefixes=CHECK %s
+
+;; -fpatchable-function-entry=0 -fcf-protection=branch
+define void @f0() "patchable-function-entry"="0" "branch-target-enforcement" {
+; CHECK-LABEL: f0:
+; CHECK-NEXT: .Lfunc_begin0:
+; CHECK:      # %bb.0:
+; CHECK-NEXT:  endbr64
+; CHECK-NEXT:  retq
+; CHECK-NOT:  .section __patchable_function_entries
+  ret void
+}
+
+;; -fpatchable-function-entry=1 -fcf-protection=branch
+define void @f1() "patchable-function-entry"="1" {
+; CHECK-LABEL: f1:
+; CHECK-NEXT: .Lfunc_begin1:
+; CHECK:       endbr64
+; CHECK-NEXT:  nop
+; CHECK-NEXT:  retq
+; CHECK:      .section __patchable_function_entries,"awo",@progbits,f1,unique,0
+; CHECK-NEXT: .p2align 3
+; CHECK-NEXT: .quad .Lfunc_begin1
+  ret void
+}
+
+;; -fpatchable-function-entry=2,1 -fcf-protection=branch
+define void @f2_1() "patchable-function-entry"="1" "patchable-function-prefix"="1" {
+; CHECK-LABEL: .type f2_1,@function
+; CHECK-NEXT: .Ltmp0:
+; CHECK-NEXT:  nop
+; CHECK-NEXT: f2_1:
+; CHECK-NEXT: .Lfunc_begin2:
+; CHECK:      # %bb.0:
+; CHECK-NEXT:  endbr64
+; CHECK-NEXT:  nop
+; CHECK-NEXT:  retq
+; CHECK:      .Lfunc_end2:
+; CHECK-NEXT: .size f2_1, .Lfunc_end2-f2_1
+; CHECK:      .section __patchable_function_entries,"awo",@progbits,f1,unique,0
+; CHECK-NEXT: .p2align 3
+; CHECK-NEXT: .quad .Ltmp0
+  ret void
+}
+
+!llvm.module.flags = !{!0}
+
+!0 = !{i32 4, !"cf-protection-branch", i32 1}

llvm/test/CodeGen/X86/patchable-function-entry.ll

@@ -24,8 +24,13 @@ define void @f1() "patchable-function-entry"="1" {
   ret void
 }
 
+;; Without -function-sections, f2 is in the same text section as f1.
+;; They share the __patchable_function_entries section.
+;; With -function-sections, f1 and f2 are in different text sections.
+;; Use separate __patchable_function_entries.
 define void @f2() "patchable-function-entry"="2" {
 ; CHECK-LABEL: f2:
+; CHECK-NEXT: .Lfunc_begin2:
 ; 32-COUNT-2:  nop
 ; 64:          xchgw %ax, %ax
 ; CHECK-NEXT:  ret
@@ -41,6 +46,7 @@ define void @f2() "patchable-function-entry"="2" {
 $f3 = comdat any
 define void @f3() "patchable-function-entry"="3" comdat {
 ; CHECK-LABEL: f3:
+; CHECK-NEXT: .Lfunc_begin3:
 ; 32-COUNT-3:  nop
 ; 64:          nopl (%rax)
 ; CHECK:       ret
@@ -56,6 +62,7 @@ define void @f3() "patchable-function-entry"="3" comdat {
 $f5 = comdat any
 define void @f5() "patchable-function-entry"="5" comdat {
 ; CHECK-LABEL: f5:
+; CHECK-NEXT: .Lfunc_begin4:
 ; 32-COUNT-5:  nop
 ; 64:          nopl 8(%rax,%rax)
 ; CHECK-NEXT:  ret
@@ -67,3 +74,29 @@ define void @f5() "patchable-function-entry"="5" comdat {
 ; 64-NEXT:     .quad .Lfunc_begin4
   ret void
 }
+
+;; -fpatchable-function-entry=3,2
+;; "patchable-function-prefix" emits data before the function entry label.
+;; We emit 1-byte NOPs before the function entry, so that with a partial patch,
+;; the remaining instructions do not need to be modified.
+define void @f3_2() "patchable-function-entry"="1" "patchable-function-prefix"="2" {
+; CHECK-LABEL: .type f3_2,@function
+; CHECK-NEXT: .Ltmp0: # @f3_2
+; CHECK-NEXT:  nop
+; CHECK-NEXT:  nop
+; CHECK-NEXT: f3_2:
+; CHECK:      # %bb.0:
+; CHECK-NEXT:  nop
+; CHECK-NEXT:  ret
+;; .size does not include the prefix.
+; CHECK:      .Lfunc_end5:
+; CHECK-NEXT: .size f3_2, .Lfunc_end5-f3_2
+; NOFSECT     .section __patchable_function_entries,"awo",@progbits,f0,unique,0
+; FSECT:      .section __patchable_function_entries,"awo",@progbits,f3_2,unique,4
+; 32:         .p2align 2
+; 32-NEXT:    .long .Ltmp0
+; 64:         .p2align 3
+; 64-NEXT:    .quad .Ltmp0
+  %frame = alloca i8, i32 16
+  ret void
+}