[llvm] r194676 - Minor extension to llvm.experimental.patchpoint: don't require a call.
Andrew Trick
atrick at apple.com
Wed Nov 13 22:54:11 PST 2013
Author: atrick
Date: Thu Nov 14 00:54:10 2013
New Revision: 194676
URL: http://llvm.org/viewvc/llvm-project?rev=194676&view=rev
Log:
Minor extension to llvm.experimental.patchpoint: don't require a call.
If a null call target is provided, don't emit a dummy call. This
allows the runtime to reserve as little nop space as it needs without
the requirement of emitting a call.
Modified:
llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
llvm/trunk/lib/Target/X86/X86MCInstLower.cpp
llvm/trunk/test/CodeGen/X86/patchpoint.ll
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp?rev=194676&r1=194675&r2=194676&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp Thu Nov 14 00:54:10 2013
@@ -6826,7 +6826,7 @@ void SelectionDAGBuilder::visitStackmap(
/// \brief Lower llvm.experimental.patchpoint directly to its target opcode.
void SelectionDAGBuilder::visitPatchpoint(const CallInst &CI) {
// void|i64 @llvm.experimental.patchpoint.void|i64(i32 <id>,
- // i32 <numNopBytes>,
+ // i32 <numBytes>,
// i8* <target>,
// i32 <numArgs>,
// [Args...],
Modified: llvm/trunk/lib/Target/X86/X86MCInstLower.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86MCInstLower.cpp?rev=194676&r1=194675&r2=194676&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86MCInstLower.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86MCInstLower.cpp Thu Nov 14 00:54:10 2013
@@ -765,6 +765,8 @@ static void LowerSTACKMAP(MCStreamer &Ou
OutStreamer.EmitInstruction(MCInstBuilder(X86::NOOP));
}
+// Lower a patchpoint of the form:
+// [<def>], <id>, <numBytes>, <target>, <numArgs>
static void LowerPATCHPOINT(MCStreamer &OutStreamer,
X86MCInstLower &MCInstLowering,
StackMaps &SM,
@@ -813,17 +815,20 @@ static void LowerPATCHPOINT(MCStreamer &
getStackMapEndMOP(MI.operands_begin(), MI.operands_end()),
isAnyRegCC && hasDef);
- // Emit MOV to materialize the target address and the CALL to target.
- // This is encoded with 12-13 bytes, depending on which register is used.
- // We conservatively assume that it is 12 bytes and emit in worst case one
- // extra NOP byte.
- unsigned EncodedBytes = 12;
- OutStreamer.EmitInstruction(MCInstBuilder(X86::MOV64ri)
- .addReg(MI.getOperand(ScratchIdx).getReg())
- .addImm(MI.getOperand(StartIdx + 2).getImm()));
- OutStreamer.EmitInstruction(MCInstBuilder(X86::CALL64r)
- .addReg(MI.getOperand(ScratchIdx).getReg()));
-
+ unsigned EncodedBytes = 0;
+ int64_t CallTarget = MI.getOperand(StartIdx + 2).getImm();
+ if (CallTarget) {
+ // Emit MOV to materialize the target address and the CALL to target.
+ // This is encoded with 12-13 bytes, depending on which register is used.
+ // We conservatively assume that it is 12 bytes and emit in worst case one
+ // extra NOP byte.
+ EncodedBytes = 12;
+ OutStreamer.EmitInstruction(MCInstBuilder(X86::MOV64ri)
+ .addReg(MI.getOperand(ScratchIdx).getReg())
+ .addImm(CallTarget));
+ OutStreamer.EmitInstruction(MCInstBuilder(X86::CALL64r)
+ .addReg(MI.getOperand(ScratchIdx).getReg()));
+ }
// Emit padding.
unsigned NumNOPBytes = MI.getOperand(StartIdx + 1).getImm();
assert(NumNOPBytes >= EncodedBytes &&
Modified: llvm/trunk/test/CodeGen/X86/patchpoint.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/patchpoint.ll?rev=194676&r1=194675&r2=194676&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/patchpoint.ll (original)
+++ llvm/trunk/test/CodeGen/X86/patchpoint.ll Thu Nov 14 00:54:10 2013
@@ -79,6 +79,22 @@ entry:
ret i64 10
}
+; Test small patchpoints that don't emit calls.
+define void @small_patchpoint_codegen(i64 %p1, i64 %p2, i64 %p3, i64 %p4) {
+entry:
+; CHECK-LABEL: small_patchpoint_codegen:
+; CHECK: Ltmp
+; CHECK: nop
+; CHECK-NEXT: nop
+; CHECK-NEXT: nop
+; CHECK-NEXT: nop
+; CHECK-NEXT: nop
+; CHECK-NEXT: popq
+; CHECK-NEXT: ret
+ %result = tail call i64 (i32, i32, i8*, i32, ...)* @llvm.experimental.patchpoint.i64(i32 5, i32 5, i8* null, i32 2, i64 %p1, i64 %p2)
+ ret void
+}
+
declare void @llvm.experimental.stackmap(i32, i32, ...)
declare void @llvm.experimental.patchpoint.void(i32, i32, i8*, i32, ...)
declare i64 @llvm.experimental.patchpoint.i64(i32, i32, i8*, i32, ...)
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