MIPS64: Port "Reland of "MIPS: Optimize load/store with large offset"".

src/mips64/assembler-mips64.cc

Index: src/mips64/assembler-mips64.cc
diff --git a/src/mips64/assembler-mips64.cc b/src/mips64/assembler-mips64.cc
index b35b166a2e3a1a75898d280d3ae7f412a70e5a53..09a19169d677454b241592a05424405c46729680 100644
--- a/src/mips64/assembler-mips64.cc
+++ b/src/mips64/assembler-mips64.cc
@@ -1940,19 +1940,42 @@ void Assembler::dlsa(Register rd, Register rt, Register rs, uint8_t sa) {
 void Assembler::LoadRegPlusOffsetToAt(const MemOperand& src) {
   DCHECK(!src.rm().is(at));
   DCHECK(is_int32(src.offset_));
-  daddiu(at, zero_reg, (src.offset_ >> kLuiShift) & kImm16Mask);
-  dsll(at, at, kLuiShift);
+  lui(at, (src.offset_ >> kLuiShift) & kImm16Mask);
   ori(at, at, src.offset_ & kImm16Mask);  // Load 32-bit offset.
   daddu(at, at, src.rm());  // Add base register.
 }
 
+// Helper for base-reg + upper part of offset, when offset is larger than int16.
+// Loads higher part of the offset to AT register.
+// Returns lower part of the offset to be used as offset
+// in Load/Store instructions
+int32_t Assembler::LoadRegPlusUpperOffsetPartToAt(const MemOperand& src) {
+  DCHECK(!src.rm().is(at));
+  DCHECK(is_int32(src.offset_));
+  int32_t hi = (src.offset_ >> kLuiShift) & kImm16Mask;
+  // If the highest bit of the lower part of the offset is 1, this would make
+  // the offset in the load/store instruction negative. We need to compensate
+  // for this by adding 1 to the upper part of the offset.
+  if (src.offset_ & kNegOffset) {
+    if ((hi & kNegOffset) != ((hi + 1) & kNegOffset)) {
+      LoadRegPlusOffsetToAt(src);
+      return 0;
+    }
+
+    hi += 1;
+  }
+
+  lui(at, hi);
+  daddu(at, at, src.rm());
+  return (src.offset_ & kImm16Mask);
+}
 
 void Assembler::lb(Register rd, const MemOperand& rs) {
   if (is_int16(rs.offset_)) {
     GenInstrImmediate(LB, rs.rm(), rd, rs.offset_);
   } else {  // Offset > 16 bits, use multiple instructions to load.
-    LoadRegPlusOffsetToAt(rs);
-    GenInstrImmediate(LB, at, rd, 0);  // Equiv to lb(rd, MemOperand(at, 0));
+    int32_t off16 = LoadRegPlusUpperOffsetPartToAt(rs);
+    GenInstrImmediate(LB, at, rd, off16);
   }
 }
 
@@ -1961,8 +1984,8 @@ void Assembler::lbu(Register rd, const MemOperand& rs) {
   if (is_int16(rs.offset_)) {
     GenInstrImmediate(LBU, rs.rm(), rd, rs.offset_);
   } else {  // Offset > 16 bits, use multiple instructions to load.
-    LoadRegPlusOffsetToAt(rs);
-    GenInstrImmediate(LBU, at, rd, 0);  // Equiv to lbu(rd, MemOperand(at, 0));
+    int32_t off16 = LoadRegPlusUpperOffsetPartToAt(rs);
+    GenInstrImmediate(LBU, at, rd, off16);
   }
 }
 
@@ -1971,8 +1994,8 @@ void Assembler::lh(Register rd, const MemOperand& rs) {
   if (is_int16(rs.offset_)) {
     GenInstrImmediate(LH, rs.rm(), rd, rs.offset_);
   } else {  // Offset > 16 bits, use multiple instructions to load.
-    LoadRegPlusOffsetToAt(rs);
-    GenInstrImmediate(LH, at, rd, 0);  // Equiv to lh(rd, MemOperand(at, 0));
+    int32_t off16 = LoadRegPlusUpperOffsetPartToAt(rs);
+    GenInstrImmediate(LH, at, rd, off16);
   }
 }
 
@@ -1981,8 +2004,8 @@ void Assembler::lhu(Register rd, const MemOperand& rs) {
   if (is_int16(rs.offset_)) {
     GenInstrImmediate(LHU, rs.rm(), rd, rs.offset_);
   } else {  // Offset > 16 bits, use multiple instructions to load.
-    LoadRegPlusOffsetToAt(rs);
-    GenInstrImmediate(LHU, at, rd, 0);  // Equiv to lhu(rd, MemOperand(at, 0));
+    int32_t off16 = LoadRegPlusUpperOffsetPartToAt(rs);
+    GenInstrImmediate(LHU, at, rd, off16);
   }
 }
 
@@ -1991,8 +2014,8 @@ void Assembler::lw(Register rd, const MemOperand& rs) {
   if (is_int16(rs.offset_)) {
     GenInstrImmediate(LW, rs.rm(), rd, rs.offset_);
   } else {  // Offset > 16 bits, use multiple instructions to load.
-    LoadRegPlusOffsetToAt(rs);
-    GenInstrImmediate(LW, at, rd, 0);  // Equiv to lw(rd, MemOperand(at, 0));
+    int32_t off16 = LoadRegPlusUpperOffsetPartToAt(rs);
+    GenInstrImmediate(LW, at, rd, off16);
   }
 }
 
@@ -2001,8 +2024,8 @@ void Assembler::lwu(Register rd, const MemOperand& rs) {
   if (is_int16(rs.offset_)) {
     GenInstrImmediate(LWU, rs.rm(), rd, rs.offset_);
   } else {  // Offset > 16 bits, use multiple instructions to load.
-    LoadRegPlusOffsetToAt(rs);
-    GenInstrImmediate(LWU, at, rd, 0);  // Equiv to lwu(rd, MemOperand(at, 0));
+    int32_t off16 = LoadRegPlusUpperOffsetPartToAt(rs);
+    GenInstrImmediate(LWU, at, rd, off16);
   }
 }
 
@@ -2025,8 +2048,8 @@ void Assembler::sb(Register rd, const MemOperand& rs) {
   if (is_int16(rs.offset_)) {
     GenInstrImmediate(SB, rs.rm(), rd, rs.offset_);
   } else {  // Offset > 16 bits, use multiple instructions to store.
-    LoadRegPlusOffsetToAt(rs);
-    GenInstrImmediate(SB, at, rd, 0);  // Equiv to sb(rd, MemOperand(at, 0));
+    int32_t off16 = LoadRegPlusUpperOffsetPartToAt(rs);
+    GenInstrImmediate(SB, at, rd, off16);
   }
 }
 
@@ -2035,8 +2058,8 @@ void Assembler::sh(Register rd, const MemOperand& rs) {
   if (is_int16(rs.offset_)) {
     GenInstrImmediate(SH, rs.rm(), rd, rs.offset_);
   } else {  // Offset > 16 bits, use multiple instructions to store.
-    LoadRegPlusOffsetToAt(rs);
-    GenInstrImmediate(SH, at, rd, 0);  // Equiv to sh(rd, MemOperand(at, 0));
+    int32_t off16 = LoadRegPlusUpperOffsetPartToAt(rs);
+    GenInstrImmediate(SH, at, rd, off16);
   }
 }
 
@@ -2045,8 +2068,8 @@ void Assembler::sw(Register rd, const MemOperand& rs) {
   if (is_int16(rs.offset_)) {
     GenInstrImmediate(SW, rs.rm(), rd, rs.offset_);
   } else {  // Offset > 16 bits, use multiple instructions to store.
-    LoadRegPlusOffsetToAt(rs);
-    GenInstrImmediate(SW, at, rd, 0);  // Equiv to sw(rd, MemOperand(at, 0));
+    int32_t off16 = LoadRegPlusUpperOffsetPartToAt(rs);
+    GenInstrImmediate(SW, at, rd, off16);
   }
 }
 
@@ -2130,8 +2153,8 @@ void Assembler::ld(Register rd, const MemOperand& rs) {
   if (is_int16(rs.offset_)) {
     GenInstrImmediate(LD, rs.rm(), rd, rs.offset_);
   } else {  // Offset > 16 bits, use multiple instructions to load.
-    LoadRegPlusOffsetToAt(rs);
-    GenInstrImmediate(LD, at, rd, 0);  // Equiv to lw(rd, MemOperand(at, 0));
+    int32_t off16 = LoadRegPlusUpperOffsetPartToAt(rs);
+    GenInstrImmediate(LD, at, rd, off16);
   }
 }
 
@@ -2140,8 +2163,8 @@ void Assembler::sd(Register rd, const MemOperand& rs) {
   if (is_int16(rs.offset_)) {
     GenInstrImmediate(SD, rs.rm(), rd, rs.offset_);
   } else {  // Offset > 16 bits, use multiple instructions to store.
-    LoadRegPlusOffsetToAt(rs);
-    GenInstrImmediate(SD, at, rd, 0);  // Equiv to sw(rd, MemOperand(at, 0));
+    int32_t off16 = LoadRegPlusUpperOffsetPartToAt(rs);
+    GenInstrImmediate(SD, at, rd, off16);
   }
 }
 
@@ -2551,8 +2574,8 @@ void Assembler::lwc1(FPURegister fd, const MemOperand& src) {
   if (is_int16(src.offset_)) {
     GenInstrImmediate(LWC1, src.rm(), fd, src.offset_);
   } else {  // Offset > 16 bits, use multiple instructions to load.
-    LoadRegPlusOffsetToAt(src);
-    GenInstrImmediate(LWC1, at, fd, 0);
+    int32_t off16 = LoadRegPlusUpperOffsetPartToAt(src);
+    GenInstrImmediate(LWC1, at, fd, off16);
   }
 }
 
@@ -2561,8 +2584,8 @@ void Assembler::ldc1(FPURegister fd, const MemOperand& src) {
   if (is_int16(src.offset_)) {
     GenInstrImmediate(LDC1, src.rm(), fd, src.offset_);
   } else {  // Offset > 16 bits, use multiple instructions to load.
-    LoadRegPlusOffsetToAt(src);
-    GenInstrImmediate(LDC1, at, fd, 0);
+    int32_t off16 = LoadRegPlusUpperOffsetPartToAt(src);
+    GenInstrImmediate(LDC1, at, fd, off16);
   }
 }
 
@@ -2571,8 +2594,8 @@ void Assembler::swc1(FPURegister fd, const MemOperand& src) {
   if (is_int16(src.offset_)) {
     GenInstrImmediate(SWC1, src.rm(), fd, src.offset_);
   } else {  // Offset > 16 bits, use multiple instructions to load.
-    LoadRegPlusOffsetToAt(src);
-    GenInstrImmediate(SWC1, at, fd, 0);
+    int32_t off16 = LoadRegPlusUpperOffsetPartToAt(src);
+    GenInstrImmediate(SWC1, at, fd, off16);
   }
 }
 
@@ -2582,8 +2605,8 @@ void Assembler::sdc1(FPURegister fd, const MemOperand& src) {
   if (is_int16(src.offset_)) {
     GenInstrImmediate(SDC1, src.rm(), fd, src.offset_);
   } else {  // Offset > 16 bits, use multiple instructions to load.
-    LoadRegPlusOffsetToAt(src);
-    GenInstrImmediate(SDC1, at, fd, 0);
+    int32_t off16 = LoadRegPlusUpperOffsetPartToAt(src);
+    GenInstrImmediate(SDC1, at, fd, off16);
   }
 }