[nfc][compiler-rt]Remove round-up in __llvm_profile_get_num_data (#83194)

- Update instrprof-basic.c as a regression test.

Author: mingmingl-llvm

compiler-rt/lib/profile/InstrProfilingBuffer.c

@@ -61,19 +61,12 @@ uint64_t __llvm_profile_get_size_for_buffer(void) {
       NamesBegin, NamesEnd, VTableBegin, VTableEnd, VNamesBegin, VNamesEnd);
 }
 
+// NOTE: Caller should guarantee that `Begin` and `End` specifies a half-open
+// interval [Begin, End). Namely, `End` is one-byte past the end of the array.
 COMPILER_RT_VISIBILITY
 uint64_t __llvm_profile_get_num_data(const __llvm_profile_data *Begin,
                                      const __llvm_profile_data *End) {
   intptr_t BeginI = (intptr_t)Begin, EndI = (intptr_t)End;
-  // `sizeof(__llvm_profile_data) - 1` is required in the numerator when
-  // [Begin, End] represents an inclusive range.
-  // For ELF, [Begin, End) represents the address of linker-inserted
-  // symbols  `__start__<elf-section>` and `__stop_<elf-section>`.
-  // Thereby, `End` is one byte past the inclusive range, and
-  // `sizeof(__llvm_profile_data) - 1` is not necessary in the numerator to get
-  // the correct number of profile data.
-  // FIXME: Consider removing `sizeof(__llvm_profile_data) - 1` if this is true
-  // across platforms.
   return ((EndI + sizeof(__llvm_profile_data) - 1) - BeginI) /
          sizeof(__llvm_profile_data);
 }

compiler-rt/test/profile/instrprof-basic.c

@@ -1,13 +1,15 @@
 // RUN: %clang_profgen -o %t -O3 %s
 // RUN: env LLVM_PROFILE_FILE=%t.profraw %run %t
 // RUN: llvm-profdata merge -o %t.profdata %t.profraw
+// RUN: llvm-profdata show --all-functions %t.profdata | FileCheck %s --check-prefix=PROFCNT
 // RUN: %clang_profuse=%t.profdata -o - -S -emit-llvm %s | FileCheck %s --check-prefix=COMMON --check-prefix=ORIG
 //
 // RUN: rm -fr %t.dir1
 // RUN: mkdir -p %t.dir1
 // RUN: env LLVM_PROFILE_FILE=%t.dir1/profraw_e_%1m %run %t
 // RUN: env LLVM_PROFILE_FILE=%t.dir1/profraw_e_%1m %run %t
 // RUN: llvm-profdata merge -o %t.em.profdata %t.dir1
+// RUN: llvm-profdata show --all-functions %t.em.profdata | FileCheck %s --check-prefix=PROFCNT
 // RUN: %clang_profuse=%t.em.profdata -o - -S -emit-llvm %s | FileCheck %s --check-prefix=COMMON --check-prefix=MERGE
 //
 // RUN: rm -fr %t.dir2
@@ -16,6 +18,7 @@
 // RUN: %run %t.merge
 // RUN: %run %t.merge
 // RUN: llvm-profdata merge -o %t.m.profdata %t.dir2/
+// RUN: llvm-profdata show --all-functions %t.m.profdata | FileCheck %s --check-prefix=PROFCNT
 // RUN: %clang_profuse=%t.m.profdata -o - -S -emit-llvm %s | FileCheck %s --check-prefix=COMMON --check-prefix=MERGE
 //
 // Test that merging is enabled by default with -fprofile-generate=
@@ -27,6 +30,7 @@
 // RUN: %run %t.merge3
 // RUN: %run %t.merge3
 // RUN: llvm-profdata merge -o %t.m3.profdata %t.dir3/
+// RUN: llvm-profdata show --all-functions %t.m3.profdata | FileCheck %s --check-prefix=PROFCNT
 // RUN: %clang_profuse=%t.m3.profdata -O0 -o - -S -emit-llvm %s | FileCheck %s --check-prefix=COMMON --check-prefix=PGOMERGE
 //
 // Test that merging is enabled by default with -fprofile-generate
@@ -40,6 +44,7 @@
 // RUN: %run %t.dir4/merge4
 // RUN: rm -f %t.dir4/merge4*
 // RUN: llvm-profdata merge -o %t.m4.profdata ./
+// RUN: llvm-profdata show --all-functions %t.m4.profdata | FileCheck %s --check-prefix=PROFCNT
 // RUN: %clang_profuse=%t.m4.profdata -O0 -o - -S -emit-llvm %s | FileCheck %s --check-prefix=COMMON  --check-prefix=PGOMERGE
 
 /// Test that the merge pool size can be larger than 10.
@@ -49,6 +54,13 @@
 // RUN: not ls %t.dir5/e_%20m.profraw
 // RUN: ls %t.dir5/e_*.profraw | count 1
 
+// Test that all three functions have counters in the profile.
+// PROFCNT-DAG: begin
+// PROFCNT-DAG: end
+// PROFCNT-DAG: main
+// PROFCNT: Functions shown: 3
+// PROFCNT: Total functions: 3
+
 int begin(int i) {
   // COMMON: br i1 %{{.*}}, label %{{.*}}, label %{{.*}}, !prof ![[PD1:[0-9]+]]
   if (i)