Improve file doesnt exist error with -fbasic-block-sections=

With -fbasicblock-sections=, let the front-end handle the case where the file
doesnt exist. The driver only checks if the option syntax is right.

Differential Revision: https://reviews.llvm.org/D89500

Author: tmsri

clang/lib/Driver/ToolChains/Clang.cpp

@@ -4924,7 +4924,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     if (Triple.isX86() && Triple.isOSBinFormatELF()) {
       StringRef Val = A->getValue();
       if (Val != "all" && Val != "labels" && Val != "none" &&
-          !(Val.startswith("list=") && llvm::sys::fs::exists(Val.substr(5))))
+          !Val.startswith("list="))
         D.Diag(diag::err_drv_invalid_value)
             << A->getAsString(Args) << A->getValue();
       else

clang/test/CodeGen/basic-block-sections.c

@@ -6,6 +6,7 @@
 // RUN: %clang_cc1 -triple x86_64 -S -fbasic-block-sections=all -o - < %s | FileCheck %s --check-prefix=BB_WORLD --check-prefix=BB_ALL
 // RUN: %clang_cc1 -triple x86_64 -S -fbasic-block-sections=list=%S/Inputs/basic-block-sections.funcnames -o - < %s | FileCheck %s --check-prefix=BB_WORLD --check-prefix=BB_LIST
 // RUN: %clang_cc1 -triple x86_64 -S -fbasic-block-sections=all -funique-basic-block-section-names -o - < %s | FileCheck %s --check-prefix=UNIQUE
+// RUN: not %clang_cc1 -fbasic-block-sections=list= -emit-obj %s 2>&1 | FileCheck %s --check-prefix=ERROR
 
 int world(int a) {
   if (a > 10)
@@ -38,3 +39,4 @@ int another(int a) {
 //
 // UNIQUE: .section .text.world.world.1,
 // UNIQUE: .section .text.another.another.1,
+// ERROR: error:  unable to load basic block sections function list: 'No such file or directory'

clang/test/Driver/fbasic-block-sections.c

@@ -4,9 +4,14 @@
 // RUN: %clang -### -target x86_64 -fbasic-block-sections=labels %s -S 2>&1 | FileCheck -check-prefix=CHECK-OPT-LABELS %s
 // RUN: not %clang -c -target arm-unknown-linux -fbasic-block-sections=all %s -S 2>&1 | FileCheck -check-prefix=CHECK-TRIPLE %s
 // RUN: not %clang -c -target x86_64-apple-darwin10 -fbasic-block-sections=all %s -S 2>&1 | FileCheck -check-prefix=CHECK-TRIPLE %s
+// RUN: %clang -### -target x86_64 -fbasic-block-sections=alll %s -S 2>&1 | FileCheck -check-prefix=CHECK-INVALID-VALUE %s
+// RUN: %clang -### -target x86_64 -fbasic-block-sections=list %s -S 2>&1 | FileCheck -check-prefix=CHECK-INVALID-VALUE %s
+// RUN: %clang -### -target x86_64 -fbasic-block-sections=list= %s -S 2>&1 | FileCheck -check-prefix=CHECK-OPT-NULL-LIST %s
 //
 // CHECK-OPT-NONE:   "-fbasic-block-sections=none"
 // CHECK-OPT-ALL:    "-fbasic-block-sections=all"
 // CHECK-OPT-LIST:   "-fbasic-block-sections={{[^ ]*}}fbasic-block-sections.c"
 // CHECK-OPT-LABELS: "-fbasic-block-sections=labels"
 // CHECK-TRIPLE:     error: unsupported option '-fbasic-block-sections=all' for target
+// CHECK-INVALID-VALUE: error: invalid value {{[^ ]*}} in '-fbasic-block-sections={{.*}}'
+// CHECK-OPT-NULL-LIST: "-fbasic-block-sections=list="