[ELF][AsmPrinter] Emit trailing dot for constant pool section when it has a hotness prefix (#150859)

Currently, `TargetLoweringObjectFileELF::getSectionForConstant` produce
`.<section>.hot` or `.<section>.unlikely` for a constant with non-empty
section prefix. This PR changes the implementation add trailing dot when
section prefix is not empty, to disambiguate `.hot` as a hotness prefix
from `.hot` as a (pure C) variable name.

Relevant discussions are in
llvm/llvm-project#148985 (comment)
and
llvm/llvm-project#148985 (comment)
and

Author: mingmingl-llvm

llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp

@@ -1060,27 +1060,27 @@ MCSection *TargetLoweringObjectFileELF::getSectionForConstant(
 
   auto &Context = getContext();
   if (Kind.isMergeableConst4() && MergeableConst4Section)
-    return Context.getELFSection(".rodata.cst4." + SectionSuffix,
+    return Context.getELFSection(".rodata.cst4." + SectionSuffix + ".",
                                  ELF::SHT_PROGBITS,
                                  ELF::SHF_ALLOC | ELF::SHF_MERGE, 4);
   if (Kind.isMergeableConst8() && MergeableConst8Section)
-    return Context.getELFSection(".rodata.cst8." + SectionSuffix,
+    return Context.getELFSection(".rodata.cst8." + SectionSuffix + ".",
                                  ELF::SHT_PROGBITS,
                                  ELF::SHF_ALLOC | ELF::SHF_MERGE, 8);
   if (Kind.isMergeableConst16() && MergeableConst16Section)
-    return Context.getELFSection(".rodata.cst16." + SectionSuffix,
+    return Context.getELFSection(".rodata.cst16." + SectionSuffix + ".",
                                  ELF::SHT_PROGBITS,
                                  ELF::SHF_ALLOC | ELF::SHF_MERGE, 16);
   if (Kind.isMergeableConst32() && MergeableConst32Section)
-    return Context.getELFSection(".rodata.cst32." + SectionSuffix,
+    return Context.getELFSection(".rodata.cst32." + SectionSuffix + ".",
                                  ELF::SHT_PROGBITS,
                                  ELF::SHF_ALLOC | ELF::SHF_MERGE, 32);
   if (Kind.isReadOnly())
-    return Context.getELFSection(".rodata." + SectionSuffix, ELF::SHT_PROGBITS,
-                                 ELF::SHF_ALLOC);
+    return Context.getELFSection(".rodata." + SectionSuffix + ".",
+                                 ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
 
   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
-  return Context.getELFSection(".data.rel.ro." + SectionSuffix,
+  return Context.getELFSection(".data.rel.ro." + SectionSuffix + ".",
                                ELF::SHT_PROGBITS,
                                ELF::SHF_ALLOC | ELF::SHF_WRITE);
 }

llvm/test/CodeGen/AArch64/constant-pool-partition.ll

@@ -19,11 +19,11 @@
 ;   function, constant pools for this constant should not have `.unlikely` suffix.
 
 ;; Constant pools for function @cold_func.
-; CHECK:       .section	.rodata.cst8.hot,"aM",@progbits,8
+; CHECK:       .section	.rodata.cst8.hot.,"aM",@progbits,8
 ; CHECK-NEXT:     .p2align
 ; CHECK-NEXT:   .LCPI0_0:
 ; CHECK-NEXT:	    .xword	0x3fe5c28f5c28f5c3              // double 0.68000000000000005
-; CHECK-NEXT: .section	.rodata.cst8.unlikely,"aM",@progbits,8
+; CHECK-NEXT: .section	.rodata.cst8.unlikely.,"aM",@progbits,8
 ; CHECK-NEXT:     .p2align
 ; CHECK-NEXT:   .LCPI0_1:
 ; CHECK-NEXT:     .xword 0x3fe5eb851eb851ec              // double 0.68500000000000005
@@ -58,7 +58,7 @@
 ; CHECK-NEXT:     .word 3                                 // 0x3
 ; CHECK-NEXT:     .word 5                                 // 0x5
 ; CHECK-NEXT:     .word 7                                 // 0x7
-; CHECK-NEXT: .section        .rodata.cst16.hot,"aM",@progbits,16
+; CHECK-NEXT: .section        .rodata.cst16.hot.,"aM",@progbits,16
 ; CHECK-NEXT:     .p2align
 ; CHECK-NEXT:   .LCPI1_2:
 ; CHECK-NEXT:     .word   442                             // 0x1ba
@@ -67,11 +67,11 @@
 ; CHECK-NEXT:     .word   0                               // 0x0
 
 ;; Constant pools for function @hot_func
-; CHECK:      .section        .rodata.cst8.hot,"aM",@progbits,8
+; CHECK:      .section        .rodata.cst8.hot.,"aM",@progbits,8
 ; CHECK-NEXT:     .p2align
 ; CHECK-NEXT:   .LCPI2_0:
 ; CHECK-NEXT:     .xword  0x3fe5c28f5c28f5c3              // double 0.68000000000000005
-; CHECK-NEXT: .section        .rodata.cst16.hot,"aM",@progbits,16
+; CHECK-NEXT: .section        .rodata.cst16.hot.,"aM",@progbits,16
 ; CHECK-NEXT:     .p2align
 ; CHECK-NEXT:   .LCPI2_1:
 ; CHECK-NEXT:     .word   0                               // 0x0

llvm/test/CodeGen/X86/constant-pool-partition.ll

@@ -24,11 +24,11 @@ target triple = "x86_64-grtev4-linux-gnu"
 ; RUN:     %s -o - 2>&1 | FileCheck %s --dump-input=always
 
 ;; For function @cold_func
-; CHECK:       .section	.rodata.cst8.hot,"aM",@progbits,8
+; CHECK:       .section	.rodata.cst8.hot.,"aM",@progbits,8
 ; CHECK-NEXT:      .p2align
 ; CHECK-NEXT:    .LCPI0_0:
 ; CHECK-NEXT:	     .quad	0x3fe5c28f5c28f5c3              # double 0.68000000000000005
-; CHECK-NEXT:  .section	.rodata.cst8.unlikely,"aM",@progbits,8
+; CHECK-NEXT:  .section	.rodata.cst8.unlikely.,"aM",@progbits,8
 ; CHECK-NEXT:      .p2align
 ; CHECK-NEXT:    .LCPI0_1:
 ; CHECK-NEXT:	     .quad	0x3eb0000000000000              # double 9.5367431640625E-7
@@ -50,11 +50,11 @@ target triple = "x86_64-grtev4-linux-gnu"
 ; CHECK-NEXT:     .long   0x3e000000              # float 0.125
 
 ;; For function @hot_func
-; CHECK:	     .section	.rodata.cst8.hot,"aM",@progbits,8
+; CHECK:	     .section	.rodata.cst8.hot.,"aM",@progbits,8
 ; CHECK-NEXT:      .p2align
 ; CHECK-NEXT:    .LCPI3_0:
 ; CHECK-NEXT:     .quad	0x3fe5c28f5c28f5c3              # double 0.68000000000000005
-; CHECK-NEXT:  .section        .rodata.cst16.hot,"aM",@progbits,16
+; CHECK-NEXT:  .section        .rodata.cst16.hot.,"aM",@progbits,16
 ; CHECK-NEXT:      .p2align
 ; CHECK-NEXT:    .LCPI3_1:
 ; CHECK-NEXT:      .long   2147483648                      # 0x80000000