ARM: Make use of d16-d31 when available.

src/arm/deoptimizer-arm.cc

Index: src/arm/deoptimizer-arm.cc
diff --git a/src/arm/deoptimizer-arm.cc b/src/arm/deoptimizer-arm.cc
index 55139dd039b752c9d5adc6643c07acad2a293df6..6e8cfde1da30e721a325df03d4d9fd9d2b6c0c04 100644
--- a/src/arm/deoptimizer-arm.cc
+++ b/src/arm/deoptimizer-arm.cc
@@ -981,22 +981,17 @@ void Deoptimizer::EntryGenerator::Generate() {
 
   if (CpuFeatures::IsSupported(VFP2)) {
     CpuFeatures::Scope scope(VFP2);
-    // Save all VFP registers before messing with them.
-    DwVfpRegister first = DwVfpRegister::FromAllocationIndex(0);
-    DwVfpRegister last =
-        DwVfpRegister::FromAllocationIndex(
-            DwVfpRegister::kMaxNumAllocatableRegisters - 1);
-    ASSERT(last.code() > first.code());
-    ASSERT((last.code() - first.code()) ==
-           (DwVfpRegister::kMaxNumAllocatableRegisters - 1));
-#ifdef DEBUG
-    int max = DwVfpRegister::kMaxNumAllocatableRegisters - 1;
-    for (int i = 0; i <= max; i++) {
-      ASSERT((DwVfpRegister::FromAllocationIndex(i).code() <= last.code()) &&
-             (DwVfpRegister::FromAllocationIndex(i).code() >= first.code()));
-    }
-#endif
-    __ vstm(db_w, sp, first, last);
+    // Save all allocatable VFP registers before messing with them.
+    ASSERT(kDoubleRegZero.code() == 14);
+    ASSERT(kScratchDoubleReg.code() == 15);
+
+    // Check CPU flags for number of registers, setting the Z condition flag.
+    __ CheckFor32DRegs(ip);
+
+    // Push registers d0-d13, and possibly d16-d31, on the stack.
+    __ vstm(db_w, sp, d16, d31, ne);
+    __ add(sp, sp, Operand(16 * kDoubleSize), LeaveCC, eq);

[Rodolph Perfetta, 2013/01/18 21:36:52]

You probably meant sub, with add you are overwriting the stack.

Why do you always make space for 32 values on the stack?

[hans, 2013/01/22 13:55:40]

Yes! I noticed this made everything crash reliably on d16 devices :)
There is an assert somewhere that checks the size of stuff on the stack. It
seemed safest to use the same stack layout in both the 16 and 32 register cases.

+    __ vstm(db_w, sp, d0, d13);
   } else {
     __ sub(sp, sp, Operand(kDoubleRegsSize));
   }
@@ -1063,7 +1058,7 @@ void Deoptimizer::EntryGenerator::Generate() {
     // Copy VFP registers to
     // double_registers_[DoubleRegister::kMaxNumAllocatableRegisters]
     int double_regs_offset = FrameDescription::double_registers_offset();
-    for (int i = 0; i < DwVfpRegister::NumAllocatableRegisters(); ++i) {
+    for (int i = 0; i < DwVfpRegister::kMaxNumAllocatableRegisters; ++i) {
       int dst_offset = i * kDoubleSize + double_regs_offset;
       int src_offset = i * kDoubleSize + kNumberOfRegisters * kPointerSize;
       __ vldr(d0, sp, src_offset);
@@ -1111,6 +1106,11 @@ void Deoptimizer::EntryGenerator::Generate() {
   }
   __ pop(r0);  // Restore deoptimizer object (class Deoptimizer).
 
+  // TODO(hans): Change the code below to not clobber r0, so that it can be
+  // used in the "restore the d registers" code further down, making this mov
+  // redundant.
+  __ mov(r4, r0);
+
   // Replace the current (input) frame with the output frames.
   Label outer_push_loop, inner_push_loop,
       outer_loop_header, inner_loop_header;
@@ -1138,6 +1138,26 @@ void Deoptimizer::EntryGenerator::Generate() {
   __ cmp(r0, r1);
   __ b(lt, &outer_push_loop);
 
+  if (CpuFeatures::IsSupported(VFP2)) {
+    CpuFeatures::Scope scope(VFP2);
+    // In case of OSR, we have to restore the d registers.
+    if (type() == OSR) {
+      // Check CPU flags for number of registers, setting the Z condition flag.
+      __ CheckFor32DRegs(ip);
+
+      __ ldr(r1, MemOperand(r4, Deoptimizer::input_offset()));
+      int src_offset = FrameDescription::double_registers_offset();
+      for (int i = 0; i < DwVfpRegister::kNumRegisters; ++i) {
+        if (i == kDoubleRegZero.code()) continue;
+        if (i == kScratchDoubleReg.code()) continue;
+
+        const DwVfpRegister reg = DwVfpRegister::from_code(i);
+        __ vldr(reg, r1, src_offset, i < 16 ? al : ne);
+        src_offset += kDoubleSize;
+      }
+    }
+  }
+
   // Push state, pc, and continuation from the last output frame.
   if (type() != OSR) {
     __ ldr(r6, MemOperand(r2, FrameDescription::state_offset()));