[llvm] [AArch64] Implement INIT/ADJUST_TRAMPOLINE (PR #70267)
Carlos Eduardo Seo via llvm-commits
llvm-commits at lists.llvm.org
Wed Oct 25 15:37:58 PDT 2023
https://github.com/ceseo created https://github.com/llvm/llvm-project/pull/70267
Add support for llvm.init.trampoline and llvm.adjust.trampoline intrinsics for AArch64.
Fixes #65573
Updates #27174
Updates #66157
>From 9e7230fe8a4bbfacbd555720cc47478cf0b343f3 Mon Sep 17 00:00:00 2001
From: Carlos Eduardo Seo <carlos.seo at linaro.org>
Date: Thu, 5 Oct 2023 19:15:57 +0000
Subject: [PATCH] [AArch64] Implement INIT/ADJUST_TRAMPOLINE
Add support for llvm.init.trampoline and llvm.adjust.trampoline intrinsics for
AArch64.
Fixes #65573
Updates #27174
Updates #66157
---
compiler-rt/lib/builtins/README.txt | 5 ++
compiler-rt/lib/builtins/trampoline_setup.c | 27 ++++++++++
.../Target/AArch64/AArch64ISelLowering.cpp | 50 +++++++++++++++++++
llvm/lib/Target/AArch64/AArch64ISelLowering.h | 2 +
4 files changed, 84 insertions(+)
diff --git a/compiler-rt/lib/builtins/README.txt b/compiler-rt/lib/builtins/README.txt
index 2d213d95f333af3..2034378f7831c02 100644
--- a/compiler-rt/lib/builtins/README.txt
+++ b/compiler-rt/lib/builtins/README.txt
@@ -272,6 +272,11 @@ switch32
switch8
switchu8
+// This function generates a custom trampoline function with the specific
+// realFunc and localsPtr values.
+void __trampoline_setup(uint32_t* trampOnStack, int trampSizeAllocated,
+ const void* realFunc, void* localsPtr);
+
// There is no C interface to the *_vfp_d8_d15_regs functions. There are
// called in the prolog and epilog of Thumb1 functions. When the C++ ABI use
// SJLJ for exceptions, each function with a catch clause or destructors needs
diff --git a/compiler-rt/lib/builtins/trampoline_setup.c b/compiler-rt/lib/builtins/trampoline_setup.c
index 844eb2794414285..71b9a7b4c755eca 100644
--- a/compiler-rt/lib/builtins/trampoline_setup.c
+++ b/compiler-rt/lib/builtins/trampoline_setup.c
@@ -41,3 +41,30 @@ COMPILER_RT_ABI void __trampoline_setup(uint32_t *trampOnStack,
__clear_cache(trampOnStack, &trampOnStack[10]);
}
#endif // __powerpc__ && !defined(__powerpc64__)
+
+// The AArch64 compiler generates calls to __trampoline_setup() when creating
+// trampoline functions on the stack for use with nested functions.
+// This function creates a custom 20-byte trampoline function on the stack
+// which loads x18 with a pointer to the outer function's locals
+// and then jumps to the target nested function.
+
+#if __aarch64__
+COMPILER_RT_ABI void __trampoline_setup(uint32_t *trampOnStack,
+ int trampSizeAllocated,
+ const void *realFunc, void *localsPtr) {
+ // should never happen, but if compiler did not allocate
+ // enough space on stack for the trampoline, abort
+ if (trampSizeAllocated < 20)
+ compilerrt_abort();
+
+ // create trampoline
+ trampOnStack[0] = 0x580000b1; // ldr x17, realFunc
+ trampOnStack[1] = 0x580000d2; // ldr x18, localsPtr
+ trampOnStack[2] = 0xd61f0220; // br x17
+ trampOnStack[3] = (uint32_t)realFunc;
+ trampOnStack[4] = (uint32_t)localsPtr;
+
+ // clear instruction cache
+ __clear_cache(trampOnStack, &trampOnStack[10]);
+}
+#endif // __aarch64__
diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
index 7211607fee528a6..58063dd2c5130eb 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -5946,6 +5946,52 @@ static SDValue LowerFLDEXP(SDValue Op, SelectionDAG &DAG) {
return Final;
}
+SDValue AArch64TargetLowering::LowerADJUST_TRAMPOLINE(SDValue Op,
+ SelectionDAG &DAG) const {
+ // Note: x18 cannot be used for the Nest parameter on Windows and macOS.
+ if (Subtarget->isTargetDarwin() || Subtarget->isTargetWindows())
+ report_fatal_error("ADJUST_TRAMPOLINE operation is only supported on Linux.");
+
+ return Op.getOperand(0);
+}
+
+SDValue AArch64TargetLowering::LowerINIT_TRAMPOLINE(SDValue Op,
+ SelectionDAG &DAG) const {
+
+ // Note: x18 cannot be used for the Nest parameter on Windows and macOS.
+ if (Subtarget->isTargetDarwin() || Subtarget->isTargetWindows())
+ report_fatal_error("INIT_TRAMPOLINE operation is only supported on Linux.");
+
+ SDValue Chain = Op.getOperand(0);
+ SDValue Trmp = Op.getOperand(1); // trampoline
+ SDValue FPtr = Op.getOperand(2); // nested function
+ SDValue Nest = Op.getOperand(3); // 'nest' parameter value
+ SDLoc dl(Op);
+
+ EVT PtrVT = getPointerTy(DAG.getDataLayout());
+ Type *IntPtrTy = DAG.getDataLayout().getIntPtrType(*DAG.getContext());
+
+ TargetLowering::ArgListTy Args;
+ TargetLowering::ArgListEntry Entry;
+
+ Entry.Ty = IntPtrTy;
+ Entry.Node = Trmp; Args.push_back(Entry);
+ Entry.Node = DAG.getConstant(20, dl, MVT::i64);
+ Args.push_back(Entry);
+
+ Entry.Node = FPtr; Args.push_back(Entry);
+ Entry.Node = Nest; Args.push_back(Entry);
+
+ // Lower to a call to __trampoline_setup(Trmp, TrampSize, FPtr, ctx_reg)
+ TargetLowering::CallLoweringInfo CLI(DAG);
+ CLI.setDebugLoc(dl).setChain(Chain).setLibCallee(
+ CallingConv::C, Type::getVoidTy(*DAG.getContext()),
+ DAG.getExternalSymbol("__trampoline_setup", PtrVT), std::move(Args));
+
+ std::pair<SDValue, SDValue> CallResult = LowerCallTo(CLI);
+ return CallResult.second;
+}
+
SDValue AArch64TargetLowering::LowerOperation(SDValue Op,
SelectionDAG &DAG) const {
LLVM_DEBUG(dbgs() << "Custom lowering: ");
@@ -5961,6 +6007,10 @@ SDValue AArch64TargetLowering::LowerOperation(SDValue Op,
return LowerGlobalAddress(Op, DAG);
case ISD::GlobalTLSAddress:
return LowerGlobalTLSAddress(Op, DAG);
+ case ISD::ADJUST_TRAMPOLINE:
+ return LowerADJUST_TRAMPOLINE(Op, DAG);
+ case ISD::INIT_TRAMPOLINE:
+ return LowerINIT_TRAMPOLINE(Op, DAG);
case ISD::SETCC:
case ISD::STRICT_FSETCC:
case ISD::STRICT_FSETCCS:
diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.h b/llvm/lib/Target/AArch64/AArch64ISelLowering.h
index 52e519cd8a0c93c..b50a63b812510d4 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.h
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.h
@@ -1045,6 +1045,8 @@ class AArch64TargetLowering : public TargetLowering {
SDValue LowerSELECT_CC(ISD::CondCode CC, SDValue LHS, SDValue RHS,
SDValue TVal, SDValue FVal, const SDLoc &dl,
SelectionDAG &DAG) const;
+ SDValue LowerINIT_TRAMPOLINE(SDValue Op, SelectionDAG &DAG) const;
+ SDValue LowerADJUST_TRAMPOLINE(SDValue Op, SelectionDAG &DAG) const;
SDValue LowerJumpTable(SDValue Op, SelectionDAG &DAG) const;
SDValue LowerBR_JT(SDValue Op, SelectionDAG &DAG) const;
SDValue LowerConstantPool(SDValue Op, SelectionDAG &DAG) const;
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