+static IntrinsicInst *FindInitTrampolineFromAlloca(Value *TrampMem) {
+ // Strip off at most one level of pointer casts, looking for an alloca. This
+ // is good enough in practice and simpler than handling any number of casts.
+ Value *Underlying = TrampMem->stripPointerCasts();
+ if (Underlying != TrampMem &&
+ (!Underlying->hasOneUse() || *Underlying->use_begin() != TrampMem))
+ return 0;
+ if (!isa<AllocaInst>(Underlying))
+ return 0;
+
+ IntrinsicInst *InitTrampoline = 0;
+ for (Value::use_iterator I = TrampMem->use_begin(), E = TrampMem->use_end();
+ I != E; I++) {
+ IntrinsicInst *II = dyn_cast<IntrinsicInst>(*I);
+ if (!II)
+ return 0;
+ if (II->getIntrinsicID() == Intrinsic::init_trampoline) {
+ if (InitTrampoline)
+ // More than one init_trampoline writes to this value. Give up.
+ return 0;
+ InitTrampoline = II;
+ continue;
+ }
+ if (II->getIntrinsicID() == Intrinsic::adjust_trampoline)
+ // Allow any number of calls to adjust.trampoline.
+ continue;
+ return 0;
+ }
+
+ // No call to init.trampoline found.
+ if (!InitTrampoline)
+ return 0;
+
+ // Check that the alloca is being used in the expected way.
+ if (InitTrampoline->getOperand(0) != TrampMem)
+ return 0;
+
+ return InitTrampoline;
+}
+
+static IntrinsicInst *FindInitTrampolineFromBB(IntrinsicInst *AdjustTramp,
+ Value *TrampMem) {
+ // Visit all the previous instructions in the basic block, and try to find a
+ // init.trampoline which has a direct path to the adjust.trampoline.
+ for (BasicBlock::iterator I = AdjustTramp,
+ E = AdjustTramp->getParent()->begin(); I != E; ) {
+ Instruction *Inst = --I;
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I))
+ if (II->getIntrinsicID() == Intrinsic::init_trampoline &&
+ II->getOperand(0) == TrampMem)
+ return II;
+ if (Inst->mayWriteToMemory())
+ return 0;
+ }
+ return 0;
+}
+
+// Given a call to llvm.adjust.trampoline, find and return the corresponding
+// call to llvm.init.trampoline if the call to the trampoline can be optimized
+// to a direct call to a function. Otherwise return NULL.
+//
+static IntrinsicInst *FindInitTrampoline(Value *Callee) {
+ Callee = Callee->stripPointerCasts();
+ IntrinsicInst *AdjustTramp = dyn_cast<IntrinsicInst>(Callee);
+ if (!AdjustTramp ||
+ AdjustTramp->getIntrinsicID() != Intrinsic::adjust_trampoline)
+ return 0;
+
+ Value *TrampMem = AdjustTramp->getOperand(0);
+
+ if (IntrinsicInst *IT = FindInitTrampolineFromAlloca(TrampMem))
+ return IT;
+ if (IntrinsicInst *IT = FindInitTrampolineFromBB(AdjustTramp, TrampMem))
+ return IT;
+ return 0;
+}
+