From 6004796d6c630696127df2494dcd4f30d1367a34 Mon Sep 17 00:00:00 2001
From: Nicolas Geoffray <ngeoffray@google.com>
Date: Mon, 15 Dec 2014 00:01:18 +0000
Subject: Don't block quick callee saved registers for optimizing.

This change builds on:
https://android-review.googlesource.com/#/c/118983/

- Also fix x86_64 assembler bug triggered by this change.
- Fix (and improve) x86's backend byte register usage.
- Fix a bug in baseline register allocator: a fixed
  out register must prevent inputs from allocating it.

Change-Id: I4883862e29b4e4b6470f1823cf7eab7e7863d8ad
---
 compiler/optimizing/code_generator.cc | 66 ++++++++++++++++++-----------------
 1 file changed, 34 insertions(+), 32 deletions(-)

(limited to 'compiler/optimizing/code_generator.cc')

diff --git a/compiler/optimizing/code_generator.cc b/compiler/optimizing/code_generator.cc
index 461409ddca..5334031dcb 100644
--- a/compiler/optimizing/code_generator.cc
+++ b/compiler/optimizing/code_generator.cc
@@ -177,6 +177,31 @@ int32_t CodeGenerator::GetStackSlot(HLocal* local) const {
   }
 }
 
+void CodeGenerator::MaybeBlockPhysicalRegisters(Location loc, bool is_output) const {
+  // The DCHECKS below check that a register is not specified twice in
+  // the summary.
+  // Note that fixed output registers are allowed to overlap with fixed input and
+  // temp registers: the writer of the location summary has to make sure they
+  // don't conflict with each other.
+  if (loc.IsRegister()) {
+    DCHECK(is_output || !blocked_core_registers_[loc.reg()]);
+    blocked_core_registers_[loc.reg()] = true;
+  } else if (loc.IsFpuRegister()) {
+    DCHECK(is_output || !blocked_fpu_registers_[loc.reg()]);
+    blocked_fpu_registers_[loc.reg()] = true;
+  } else if (loc.IsFpuRegisterPair()) {
+    DCHECK(is_output || !blocked_fpu_registers_[loc.AsFpuRegisterPairLow<int>()]);
+    blocked_fpu_registers_[loc.AsFpuRegisterPairLow<int>()] = true;
+    DCHECK(is_output || !blocked_fpu_registers_[loc.AsFpuRegisterPairHigh<int>()]);
+    blocked_fpu_registers_[loc.AsFpuRegisterPairHigh<int>()] = true;
+  } else if (loc.IsRegisterPair()) {
+    DCHECK(is_output || !blocked_core_registers_[loc.AsRegisterPairLow<int>()]);
+    blocked_core_registers_[loc.AsRegisterPairLow<int>()] = true;
+    DCHECK(is_output || !blocked_core_registers_[loc.AsRegisterPairHigh<int>()]);
+    blocked_core_registers_[loc.AsRegisterPairHigh<int>()] = true;
+  }
+}
+
 void CodeGenerator::AllocateRegistersLocally(HInstruction* instruction) const {
   LocationSummary* locations = instruction->GetLocations();
   if (locations == nullptr) return;
@@ -196,43 +221,18 @@ void CodeGenerator::AllocateRegistersLocally(HInstruction* instruction) const {
   // Mark all fixed input, temp and output registers as used.
   for (size_t i = 0, e = locations->GetInputCount(); i < e; ++i) {
     Location loc = locations->InAt(i);
-    // The DCHECKS below check that a register is not specified twice in
-    // the summary.
-    if (loc.IsRegister()) {
-      DCHECK(!blocked_core_registers_[loc.reg()]);
-      blocked_core_registers_[loc.reg()] = true;
-    } else if (loc.IsFpuRegister()) {
-      DCHECK(!blocked_fpu_registers_[loc.reg()]);
-      blocked_fpu_registers_[loc.reg()] = true;
-    } else if (loc.IsFpuRegisterPair()) {
-      DCHECK(!blocked_fpu_registers_[loc.AsFpuRegisterPairLow<int>()]);
-      blocked_fpu_registers_[loc.AsFpuRegisterPairLow<int>()] = true;
-      DCHECK(!blocked_fpu_registers_[loc.AsFpuRegisterPairHigh<int>()]);
-      blocked_fpu_registers_[loc.AsFpuRegisterPairHigh<int>()] = true;
-    } else if (loc.IsRegisterPair()) {
-      DCHECK(!blocked_core_registers_[loc.AsRegisterPairLow<int>()]);
-      blocked_core_registers_[loc.AsRegisterPairLow<int>()] = true;
-      DCHECK(!blocked_core_registers_[loc.AsRegisterPairHigh<int>()]);
-      blocked_core_registers_[loc.AsRegisterPairHigh<int>()] = true;
-    }
+    MaybeBlockPhysicalRegisters(loc, false);
   }
 
   for (size_t i = 0, e = locations->GetTempCount(); i < e; ++i) {
     Location loc = locations->GetTemp(i);
-    // The DCHECKS below check that a register is not specified twice in
-    // the summary.
-    if (loc.IsRegister()) {
-      DCHECK(!blocked_core_registers_[loc.reg()]);
-      blocked_core_registers_[loc.reg()] = true;
-    } else if (loc.IsFpuRegister()) {
-      DCHECK(!blocked_fpu_registers_[loc.reg()]);
-      blocked_fpu_registers_[loc.reg()] = true;
-    } else {
-      DCHECK(loc.GetPolicy() == Location::kRequiresRegister
-             || loc.GetPolicy() == Location::kRequiresFpuRegister);
-    }
+    MaybeBlockPhysicalRegisters(loc, false);
   }
 
+  // If the output is a fixed register, mark it as used.
+  Location result_location = locations->Out();
+  MaybeBlockPhysicalRegisters(result_location, true);
+
   SetupBlockedRegisters();
 
   // Allocate all unallocated input locations.
@@ -276,9 +276,11 @@ void CodeGenerator::AllocateRegistersLocally(HInstruction* instruction) const {
                      << loc.GetPolicy();
       }
       locations->SetTempAt(i, loc);
+    } else {
+      DCHECK(loc.IsFpuRegister() || loc.IsRegister());
     }
   }
-  Location result_location = locations->Out();
+
   if (result_location.IsUnallocated()) {
     switch (result_location.GetPolicy()) {
       case Location::kAny:
-- 
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