Support -mnop-mcount and -mrecord-mcount on x86_64 elf targets.

clang/lib/Driver/ToolChains/Clang.cpp

@@ -6884,14 +6884,16 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
             << A->getAsString(Args) << TripleStr;
     }
     if (Arg *A = Args.getLastArg(options::OPT_mnop_mcount)) {
-      if (Arch == llvm::Triple::systemz)
+      if (Arch == llvm::Triple::systemz ||
+          (TC.getTriple().isX86_64() && TC.getTriple().isOSBinFormatELF()))
         A->render(Args, CmdArgs);
       else
         D.Diag(diag::err_drv_unsupported_opt_for_target)
             << A->getAsString(Args) << TripleStr;
     }
     if (Arg *A = Args.getLastArg(options::OPT_mrecord_mcount)) {
-      if (Arch == llvm::Triple::systemz)
+      if (Arch == llvm::Triple::systemz ||
+          (TC.getTriple().isX86_64() && TC.getTriple().isOSBinFormatELF()))
         A->render(Args, CmdArgs);
       else
         D.Diag(diag::err_drv_unsupported_opt_for_target)

clang/test/CodeGen/mnop-mcount.c

@@ -6,6 +6,14 @@
 // RUN:   %s 2>&1 | FileCheck -check-prefix=NOPG %s
 // RUN: %clang_cc1 -mnop-mcount -triple s390x-ibm-linux -emit-llvm -o - %s \
 // RUN:   2>&1 | FileCheck -check-prefix=NOPG %s
+// RUN: %clang_cc1 -pg -mfentry -mnop-mcount -triple x86_64-ibm-linux -emit-llvm \
+// RUN:   -o - %s 2>&1 | FileCheck  %s
+// RUN: not %clang_cc1 -pg -mnop-mcount -triple x86_64-ibm-linux -emit-llvm -o - \
+// RUN:   %s 2>&1 | FileCheck -check-prefix=NOMFENTRY %s
+// RUN: %clang_cc1 -mfentry -mnop-mcount -triple x86_64-ibm-linux -emit-llvm -o - \
+// RUN:   %s 2>&1 | FileCheck -check-prefix=NOPG %s
+// RUN: %clang_cc1 -mnop-mcount -triple x86_64-ibm-linux -emit-llvm -o - %s \
+// RUN:   2>&1 | FileCheck -check-prefix=NOPG %s
 
 int foo(void) {
   return 0;

clang/test/CodeGen/mrecord-mcount.c

@@ -6,6 +6,14 @@
 // RUN:   %s 2>&1 | FileCheck -check-prefix=NOPG %s
 // RUN: %clang_cc1 -mrecord-mcount -triple s390x-ibm-linux -emit-llvm -o - %s \
 // RUN:   2>&1 | FileCheck -check-prefix=NOPG %s
+// RUN: %clang_cc1 -pg -mfentry -mrecord-mcount -triple x86_64-ibm-linux -emit-llvm \
+// RUN:   -o - %s 2>&1 | FileCheck  %s
+// RUN: not %clang_cc1 -pg -mrecord-mcount -triple x86_64-ibm-linux -emit-llvm -o - \
+// RUN:   %s 2>&1 | FileCheck -check-prefix=NOMFENTRY %s
+// RUN: %clang_cc1 -mfentry -mrecord-mcount -triple x86_64-ibm-linux -emit-llvm -o - \
+// RUN:   %s 2>&1 | FileCheck -check-prefix=NOPG %s
+// RUN: %clang_cc1 -mrecord-mcount -triple x86_64-ibm-linux -emit-llvm -o - %s \
+// RUN:   2>&1 | FileCheck -check-prefix=NOPG %s
 
 int foo(void) {
   return 0;

clang/test/Driver/mcount.c

@@ -1,12 +1,10 @@
 // RUN: %clang --target=s390x -c -### %s -mnop-mcount -mrecord-mcount 2>&1 | FileCheck %s
+// RUN: %clang --target=x86_64 -c -### %s -mnop-mcount -mrecord-mcount 2>&1 | FileCheck %s
 
 // CHECK: "-mnop-mcount"
 // CHECK: "-mrecord-mcount"
 
-// RUN: not %clang --target=x86_64 -c -### %s -mnop-mcount -mrecord-mcount 2>&1 | FileCheck --check-prefix=ERR1 %s
 // RUN: not %clang --target=aarch64 -c -### %s -mnop-mcount -mrecord-mcount 2>&1 | FileCheck --check-prefix=ERR2 %s
 
-// ERR1: error: unsupported option '-mnop-mcount' for target 'x86_64'
-// ERR1: error: unsupported option '-mrecord-mcount' for target 'x86_64'
 // ERR2: error: unsupported option '-mnop-mcount' for target 'aarch64'
 // ERR2: error: unsupported option '-mrecord-mcount' for target 'aarch64'

llvm/lib/Target/X86/X86ISelDAGToDAG.cpp

@@ -179,11 +179,19 @@ namespace {
     bool runOnMachineFunction(MachineFunction &MF) override {
       // Reset the subtarget each time through.
       Subtarget = &MF.getSubtarget<X86Subtarget>();
-      IndirectTlsSegRefs = MF.getFunction().hasFnAttribute(
-                             "indirect-tls-seg-refs");
+      const Function &F = MF.getFunction();
+
+      IndirectTlsSegRefs = F.hasFnAttribute("indirect-tls-seg-refs");
+
+      if (F.getFnAttribute("fentry-call").getValueAsString() != "true") {
+        if (F.hasFnAttribute("mnop-mcount"))
+          report_fatal_error("mnop-mcount only supported with fentry-call");
+        if (F.hasFnAttribute("mrecord-mcount"))
+          report_fatal_error("mrecord-mcount only supported with fentry-call");
+      }
 
       // OptFor[Min]Size are used in pattern predicates that isel is matching.
-      OptForMinSize = MF.getFunction().hasMinSize();
+      OptForMinSize = F.hasMinSize();
       return SelectionDAGISel::runOnMachineFunction(MF);
     }
 

llvm/lib/Target/X86/X86MCInstLower.cpp

@@ -26,6 +26,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/BinaryFormat/ELF.h"
 #include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
 #include "llvm/CodeGen/MachineConstantPool.h"
 #include "llvm/CodeGen/MachineFunction.h"
@@ -44,6 +45,7 @@
 #include "llvm/MC/MCInst.h"
 #include "llvm/MC/MCInstBuilder.h"
 #include "llvm/MC/MCSection.h"
+#include "llvm/MC/MCSectionELF.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/MC/TargetRegistry.h"
@@ -885,6 +887,22 @@ void X86AsmPrinter::LowerFENTRY_CALL(const MachineInstr &MI,
                                      X86MCInstLower &MCIL) {
   bool Is64Bits = Subtarget->is64Bit();
   MCContext &Ctx = OutStreamer->getContext();
+
+  if (MF->getFunction().hasFnAttribute("mrecord-mcount")) {
+    MCSymbol *DotSym = OutContext.createTempSymbol();
+    OutStreamer->pushSection();
+    OutStreamer->switchSection(
+        Ctx.getELFSection("__mcount_loc", ELF::SHT_PROGBITS, ELF::SHF_ALLOC));
+    OutStreamer->emitSymbolValue(DotSym, Is64Bits ? 8 : 4);
+    OutStreamer->popSection();
+    OutStreamer->emitLabel(DotSym);
+  }
+
+  if (MF->getFunction().hasFnAttribute("mnop-mcount")) {
+    emitX86Nops(*OutStreamer, 5, Subtarget);
+    return;
+  }
+
   MCSymbol *fentry = Ctx.getOrCreateSymbol("__fentry__");
   const MCSymbolRefExpr *Op = MCSymbolRefExpr::create(fentry, Ctx);
 

llvm/test/CodeGen/X86/mnop-mcount-01.ll

@@ -0,0 +1,26 @@
+; RUN: llc %s -mtriple=x86_64-linux-gnu -o - -verify-machineinstrs \
+; RUN:   | FileCheck %s
+
+define void @test1() #0 {
+entry:
+  ret void
+
+; CHECK-LABEL: @test1
+; CHECK: callq __fentry__
+; CHECK-NOT: nopl 8(%rax,%rax)
+; CHECK: retq
+}
+
+define void @test2() #1 {
+entry:
+  ret void
+
+; CHECK-LABEL: @test2
+; CHECK-NOT: callq __fentry__
+; CHECK: nopl 8(%rax,%rax)
+; CHECK: retq
+}
+
+attributes #0 = { "fentry-call"="true" }
+attributes #1 = { "fentry-call"="true" "mnop-mcount" }
+

llvm/test/CodeGen/X86/mnop-mcount-02.ll

@@ -0,0 +1,10 @@
+; RUN: not --crash llc %s -mtriple=x86_64-linux-gnu -o - 2>&1 | FileCheck %s
+;
+; CHECK: LLVM ERROR: mnop-mcount only supported with fentry-call
+
+define void @test1() #0 {
+entry:
+  ret void
+}
+
+attributes #0 = { "instrument-function-entry-inlined"="mcount" "mnop-mcount" }

llvm/test/CodeGen/X86/mrecord-mcount-01.ll

@@ -0,0 +1,32 @@
+; RUN: llc %s -mtriple=x86_64-linux-gnu -o - -verify-machineinstrs \
+; RUN:   | FileCheck %s
+
+define void @test1() #0 {
+entry:
+  ret void
+
+; CHECK-LABEL: test1:
+; CHECK: .section __mcount_loc,"a",@progbits
+; CHECK: .quad .Ltmp0
+; CHECK: .text
+; CHECK: .Ltmp0:
+; CHECK: callq __fentry__
+; CHECK: retq 
+}
+
+define void @test2() #1 {
+entry:
+  ret void
+
+; CHECK-LABEL: test2:
+; CHECK: .section __mcount_loc,"a",@progbits
+; CHECK: .quad .Ltmp1
+; CHECK: .text
+; CHECK: .Ltmp1:
+; CHECK: nopl 8(%rax,%rax)
+; CHECK-NOT: callq __fentry__
+; CHECK: retq
+}
+
+attributes #0 = { "fentry-call"="true" "mrecord-mcount" }
+attributes #1 = { "fentry-call"="true" "mnop-mcount" "mrecord-mcount" }

llvm/test/CodeGen/X86/mrecord-mcount-02.ll

@@ -0,0 +1,10 @@
+; RUN: not --crash llc %s -mtriple=x86_64-linux-gnu -o - 2>&1 | FileCheck %s
+;
+; CHECK: LLVM ERROR: mrecord-mcount only supported with fentry-call
+
+define void @test1() #0 {
+entry:
+  ret void
+}
+
+attributes #0 = { "instrument-function-entry-inlined"="mcount" "mrecord-mcount" }