Avoid unnecessary copy/load in EvalLoc() and LoadValue().

EvalLoc()/EvalLocWide() are used to prepare a register where
a value is subsequently stored, so they shouldn't copy the
old value to the new register for register class mismatch.

The only exception where we actually need a copy is
LoadValue()/LoadValueWide(), so we inline the old code that
makes the copy there. We also avoid loading inexpensive
constants when the value is already in the register.

Change-Id: I07519e9d4d9b3f7272233d196435f3035e4a3ca9

4 files changed, 44 insertions, 19 deletions

diff --git a/compiler/dex/quick/gen_loadstore.cc b/compiler/dex/quick/gen_loadstore.cc
index faa9461728..8fcb09b955 100644
--- a/compiler/dex/quick/gen_loadstore.cc
+++ b/compiler/dex/quick/gen_loadstore.cc
@@ -139,12 +139,25 @@ void Mir2Lir::LoadValueDirectWideFixed(RegLocation rl_src, RegStorage r_dest) {
 }
 
 RegLocation Mir2Lir::LoadValue(RegLocation rl_src, RegisterClass op_kind) {
-  rl_src = EvalLoc(rl_src, op_kind, false);
-  if (IsInexpensiveConstant(rl_src) || rl_src.location != kLocPhysReg) {
-    LoadValueDirect(rl_src, rl_src.reg);
-    rl_src.location = kLocPhysReg;
-    MarkLive(rl_src);
+  rl_src = UpdateLoc(rl_src);
+  if (rl_src.location == kLocPhysReg) {
+    if (!RegClassMatches(op_kind, rl_src.reg)) {
+      // Wrong register class, realloc, copy and transfer ownership.
+      RegStorage new_reg = AllocTypedTemp(rl_src.fp, op_kind);
+      OpRegCopy(new_reg, rl_src.reg);
+      // Associate the old sreg with the new register and clobber the old register.
+      GetRegInfo(new_reg)->SetSReg(GetRegInfo(rl_src.reg)->SReg());
+      Clobber(rl_src.reg);
+      rl_src.reg = new_reg;
+    }
+    return rl_src;
   }
+
+  DCHECK_NE(rl_src.s_reg_low, INVALID_SREG);
+  rl_src.reg = AllocTypedTemp(rl_src.fp, op_kind);
+  LoadValueDirect(rl_src, rl_src.reg);
+  rl_src.location = kLocPhysReg;
+  MarkLive(rl_src);
   return rl_src;
 }
 
@@ -203,12 +216,26 @@ void Mir2Lir::StoreValue(RegLocation rl_dest, RegLocation rl_src) {
 
 RegLocation Mir2Lir::LoadValueWide(RegLocation rl_src, RegisterClass op_kind) {
   DCHECK(rl_src.wide);
-  rl_src = EvalLoc(rl_src, op_kind, false);
-  if (IsInexpensiveConstant(rl_src) || rl_src.location != kLocPhysReg) {
-    LoadValueDirectWide(rl_src, rl_src.reg);
-    rl_src.location = kLocPhysReg;
-    MarkLive(rl_src);
+  rl_src = UpdateLocWide(rl_src);
+  if (rl_src.location == kLocPhysReg) {
+    if (!RegClassMatches(op_kind, rl_src.reg)) {
+      // Wrong register class, realloc, copy and transfer ownership.
+      RegStorage new_regs = AllocTypedTempWide(rl_src.fp, op_kind);
+      OpRegCopyWide(new_regs, rl_src.reg);
+      // Associate the old sreg with the new register and clobber the old register.
+      GetRegInfo(new_regs)->SetSReg(GetRegInfo(rl_src.reg)->SReg());
+      Clobber(rl_src.reg);
+      rl_src.reg = new_regs;
+    }
+    return rl_src;
   }
+
+  DCHECK_NE(rl_src.s_reg_low, INVALID_SREG);
+  DCHECK_NE(GetSRegHi(rl_src.s_reg_low), INVALID_SREG);
+  rl_src.reg = AllocTypedTempWide(rl_src.fp, op_kind);
+  LoadValueDirectWide(rl_src, rl_src.reg);
+  rl_src.location = kLocPhysReg;
+  MarkLive(rl_src);
   return rl_src;
 }
 
diff --git a/compiler/dex/quick/mir_to_lir.h b/compiler/dex/quick/mir_to_lir.h
index 74245a4a06..5a824e7215 100644
--- a/compiler/dex/quick/mir_to_lir.h
+++ b/compiler/dex/quick/mir_to_lir.h
@@ -673,9 +673,9 @@ class Mir2Lir : public Backend {
     RegLocation UpdateRawLoc(RegLocation loc);
 
     /**
-     * @brief Used to load register location into a typed temporary or pair of temporaries.
+     * @brief Used to prepare a register location to receive a wide value.
      * @see EvalLoc
-     * @param loc The register location to load from.
+     * @param loc the location where the value will be stored.
      * @param reg_class Type of register needed.
      * @param update Whether the liveness information should be updated.
      * @return Returns the properly typed temporary in physical register pairs.
@@ -683,8 +683,8 @@ class Mir2Lir : public Backend {
     RegLocation EvalLocWide(RegLocation loc, int reg_class, bool update);
 
     /**
-     * @brief Used to load register location into a typed temporary.
-     * @param loc The register location to load from.
+     * @brief Used to prepare a register location to receive a value.
+     * @param loc the location where the value will be stored.
      * @param reg_class Type of register needed.
      * @param update Whether the liveness information should be updated.
      * @return Returns the properly typed temporary in physical register.
diff --git a/compiler/dex/quick/ralloc_util.cc b/compiler/dex/quick/ralloc_util.cc
index ca9a3ab64f..04de286ae2 100644
--- a/compiler/dex/quick/ralloc_util.cc
+++ b/compiler/dex/quick/ralloc_util.cc
@@ -937,9 +937,8 @@ RegLocation Mir2Lir::EvalLocWide(RegLocation loc, int reg_class, bool update) {
   /* If already in registers, we can assume proper form.  Right reg class? */
   if (loc.location == kLocPhysReg) {
     if (!RegClassMatches(reg_class, loc.reg)) {
-      /* Wrong register class.  Reallocate and copy */
+      // Wrong register class.  Reallocate and transfer ownership.
       RegStorage new_regs = AllocTypedTempWide(loc.fp, reg_class);
-      OpRegCopyWide(new_regs, loc.reg);
       // Associate the old sreg with the new register and clobber the old register.
       GetRegInfo(new_regs)->SetSReg(GetRegInfo(loc.reg)->SReg());
       Clobber(loc.reg);
@@ -971,9 +970,8 @@ RegLocation Mir2Lir::EvalLoc(RegLocation loc, int reg_class, bool update) {
 
   if (loc.location == kLocPhysReg) {
     if (!RegClassMatches(reg_class, loc.reg)) {
-      /* Wrong register class.  Realloc, copy and transfer ownership */
+      // Wrong register class.  Reallocate and transfer ownership.
       RegStorage new_reg = AllocTypedTemp(loc.fp, reg_class);
-      OpRegCopy(new_reg, loc.reg);
       // Associate the old sreg with the new register and clobber the old register.
       GetRegInfo(new_reg)->SetSReg(GetRegInfo(loc.reg)->SReg());
       Clobber(loc.reg);
diff --git a/compiler/dex/quick/x86/int_x86.cc b/compiler/dex/quick/x86/int_x86.cc
index 698fce4178..b6e0841e6e 100644
--- a/compiler/dex/quick/x86/int_x86.cc
+++ b/compiler/dex/quick/x86/int_x86.cc
@@ -1196,7 +1196,7 @@ void X86Mir2Lir::GenLongRegOrMemOp(RegLocation rl_dest, RegLocation rl_src,
   if (rl_src.location == kLocPhysReg) {
     // Both operands are in registers.
     // But we must ensure that rl_src is in pair
-    rl_src = EvalLocWide(rl_src, kCoreReg, true);
+    rl_src = LoadValueWide(rl_src, kCoreReg);
     if (rl_dest.reg.GetLowReg() == rl_src.reg.GetHighReg()) {
       // The registers are the same, so we would clobber it before the use.
       RegStorage temp_reg = AllocTemp();