rewriter: factor out call setup code, fix scratch validation test + add assembler::skipBytes()

src/asm_writing/assembler.cpp

@@ -1034,6 +1034,16 @@ void Assembler::emitAnnotation(int num) {
     nop();
 }
 
+void Assembler::skipBytes(int num) {
+    if (addr + num >= end_addr) {
+        addr = end_addr;
+        failed = true;
+        return;
+    }
+
+    addr += num;
+}
+
 ForwardJump::ForwardJump(Assembler& assembler, ConditionCode condition)
     : assembler(assembler), condition(condition), jmp_inst(assembler.curInstPointer()) {
     assembler.jmp_cond(JumpDestination::fromStart(assembler.bytesWritten() + max_jump_size), condition);

src/asm_writing/assembler.h

@@ -193,6 +193,7 @@ public:
     void fillWithNops();
     void fillWithNopsExcept(int bytes);
     void emitAnnotation(int num);
+    void skipBytes(int num);
 
     uint8_t* startAddr() const { return start_addr; }
     int bytesLeft() const { return end_addr - addr; }

src/asm_writing/rewriter.cpp

@@ -792,10 +792,8 @@ RewriterVar* Rewriter::call(bool has_side_effects, void* func_addr, const Rewrit
     return result;
 }
 
-void Rewriter::_call(RewriterVar* result, bool has_side_effects, void* func_addr, const RewriterVar::SmallVector& args,
-                     const RewriterVar::SmallVector& args_xmm) {
-    assembler->comment("_call");
-
+void Rewriter::_setupCall(RewriterVar* result, bool has_side_effects, const RewriterVar::SmallVector& args,
+                          const RewriterVar::SmallVector& args_xmm) {
     if (has_side_effects)
         assert(done_guarding);
 
@@ -828,9 +826,6 @@ void Rewriter::_call(RewriterVar* result, bool has_side_effects, void* func_addr
         }
     }
 
-    // RewriterVarUsage scratch = createNewVar(Location::any());
-    assembler::Register r = allocReg(assembler::R11);
-
     for (int i = 0; i < args.size(); i++) {
         Location l(Location::forArg(i));
         RewriterVar* var = args[i];
@@ -950,6 +945,19 @@ void Rewriter::_call(RewriterVar* result, bool has_side_effects, void* func_addr
         assert(!l.isClobberedByCall());
     }
 #endif
+}
+
+void Rewriter::_call(RewriterVar* result, bool has_side_effects, void* func_addr, const RewriterVar::SmallVector& args,
+                     const RewriterVar::SmallVector& args_xmm) {
+    assembler->comment("_call");
+
+    // RewriterVarUsage scratch = createNewVar(Location::any());
+    assembler::Register r = allocReg(assembler::R11);
+
+    _setupCall(result, has_side_effects, args, args_xmm);
+
+    // make sure setupCall doesn't use R11
+    assert(vars_by_location.count(assembler::R11) == 0);
 
     uint64_t asm_address = (uint64_t)assembler->curInstPointer() + 5;
     uint64_t real_asm_address = asm_address + (uint64_t)rewrite->getSlotStart() - (uint64_t)assembler->startAddr();
@@ -1737,10 +1745,10 @@ Rewriter::Rewriter(std::unique_ptr<ICSlotRewrite> rewrite, int num_args, const s
     // the entire scratch space.
     bool VALIDATE_SCRATCH_SPACE = false;
     if (VALIDATE_SCRATCH_SPACE) {
-        int scratch_size = rewrite->getScratchSize();
+        int scratch_size = this->rewrite->getScratchSize();
         for (int i = 0; i < scratch_size; i += 8) {
             assembler->movq(assembler::Immediate(0x12345678UL),
-                            assembler::Indirect(assembler::RSP, i + rewrite->getScratchRspOffset()));
+                            assembler::Indirect(assembler::RSP, i + this->rewrite->getScratchRspOffset()));
         }
     }
 }

src/asm_writing/rewriter.h

@@ -19,6 +19,7 @@
 #include <memory>
 #include <tuple>
 
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallSet.h"
 
@@ -349,7 +350,7 @@ protected:
     Rewriter(std::unique_ptr<ICSlotRewrite> rewrite, int num_args, const std::vector<int>& live_outs);
 
     llvm::SmallVector<RewriterAction, 32> actions;
-    void addAction(std::function<void()> action, std::vector<RewriterVar*> const& vars, ActionType type) {
+    void addAction(std::function<void()> action, llvm::ArrayRef<RewriterVar*> vars, ActionType type) {
         assertPhaseCollecting();
         for (RewriterVar* var : vars) {
             assert(var != NULL);
@@ -413,6 +414,8 @@ protected:
 
     void _trap();
     void _loadConst(RewriterVar* result, int64_t val);
+    void _setupCall(RewriterVar* result, bool has_side_effects, const RewriterVar::SmallVector& args,
+                    const RewriterVar::SmallVector& args_xmm);
     void _call(RewriterVar* result, bool has_side_effects, void* func_addr, const RewriterVar::SmallVector& args,
                const RewriterVar::SmallVector& args_xmm);
     void _add(RewriterVar* result, RewriterVar* a, int64_t b, Location dest);