/// bytes. Return the size of nop emitted.
static unsigned EmitNop(MCStreamer &OS, unsigned NumBytes, bool Is64Bit,
const MCSubtargetInfo &STI) {
- // This works only for 64bit. For 32bit we have to do additional checking if
- // the CPU supports multi-byte nops.
- assert(Is64Bit && "EmitNops only supports X86-64");
+ if (!Is64Bit) {
+ // TODO Do additional checking if the CPU supports multi-byte nops.
+ OS.EmitInstruction(MCInstBuilder(X86::NOOP), STI);
+ return 1;
+ }
unsigned NopSize;
unsigned Opc, BaseReg, ScaleVal, IndexReg, Displacement, SegmentReg;
NoAutoPaddingScope NoPadScope(*OutStreamer);
+ const Function &F = MF->getFunction();
+ if (F.hasFnAttribute("patchable-function-entry")) {
+ unsigned Num;
+ if (F.getFnAttribute("patchable-function-entry")
+ .getValueAsString()
+ .getAsInteger(10, Num))
+ return;
+ EmitNops(*OutStreamer, Num, Subtarget->is64Bit(), getSubtargetInfo());
+ return;
+ }
// We want to emit the following pattern:
//
// .p2align 1, ...
--- /dev/null
+; RUN: llc -mtriple=i386 %s -o - | FileCheck --check-prefixes=CHECK,NOFSECT,32 %s
+; RUN: llc -mtriple=x86_64 %s -o - | FileCheck --check-prefixes=CHECK,NOFSECT,64 %s
+
+define void @f0() "patchable-function-entry"="0" {
+; CHECK-LABEL: f0:
+; CHECK-NEXT: .Lfunc_begin0:
+; CHECK-NOT: nop
+; CHECK: ret
+; CHECK: .section __patchable_function_entries,"awo",@progbits,f0,unique,0
+; 32: .p2align 2
+; 32-NEXT: .long .Lfunc_begin0
+; 64: .p2align 3
+; 64-NEXT: .quad .Lfunc_begin0
+ ret void
+}
+
+define void @f1() "patchable-function-entry"="1" {
+; CHECK-LABEL: f1:
+; CHECK: nop
+; CHECK-NEXT: ret
+; NOFSECT: .section __patchable_function_entries,"awo",@progbits,f0,unique,0
+; FSECT: .section __patchable_function_entries,"awo",@progbits,f1,unique,1
+; 32: .p2align 2
+; 32-NEXT: .long .Lfunc_begin1
+; 64: .p2align 3
+; 64-NEXT: .quad .Lfunc_begin1
+ ret void
+}
+
+$f3 = comdat any
+define void @f3() "patchable-function-entry"="3" comdat {
+; CHECK-LABEL: f3:
+; 32-COUNT-3: nop
+; 64: nopl (%rax)
+; CHECK: ret
+; NOFSECT: .section __patchable_function_entries,"aGwo",@progbits,f3,comdat,f3,unique,1
+; FSECT: .section __patchable_function_entries,"aGwo",@progbits,f3,comdat,f3,unique,2
+; 32: .p2align 2
+; 32-NEXT: .long .Lfunc_begin2
+; 64: .p2align 3
+; 64-NEXT: .quad .Lfunc_begin2
+ ret void
+}
+
+$f5 = comdat any
+define void @f5() "patchable-function-entry"="5" comdat {
+; CHECK-LABEL: f5:
+; 32-COUNT-5: nop
+; 64: nopl 8(%rax,%rax)
+; CHECK-NEXT: ret
+; NOFSECT .section __patchable_function_entries,"aGwo",@progbits,f5,comdat,f5,unique,2
+; FSECT: .section __patchable_function_entries,"aGwo",@progbits,f5,comdat,f5,unique,3
+; 32: .p2align 2
+; 32-NEXT: .long .Lfunc_begin3
+; 64: .p2align 3
+; 64-NEXT: .quad .Lfunc_begin3
+ ret void
+}