Changeset 50553 in webkit for trunk/JavaScriptCore/assembler

Timestamp:

Nov 5, 2009, 12:28:02 AM (16 years ago)

Author:

[email protected]

Message:

Use ARMv7 specific encoding for immediate constants on ARMv7 target
​https://bugs.webkit.org/show_bug.cgi?id=31060

Patch by Gabor Loki <​[email protected]> on 2009-11-05
Reviewed by Gavin Barraclough.

• assembler/ARMAssembler.cpp:

(JSC::ARMAssembler::getOp2): Use INVALID_IMM
(JSC::ARMAssembler::getImm): Use encodeComplexImm for complex immediate
(JSC::ARMAssembler::moveImm): Ditto.
(JSC::ARMAssembler::encodeComplexImm): Encode a constant by one or two
instructions or a PC relative load.

• assembler/ARMAssembler.h: Use INVALID_IMM if a constant cannot be

encoded as an immediate constant.
(JSC::ARMAssembler::):
(JSC::ARMAssembler::movw_r): 16-bit immediate load
(JSC::ARMAssembler::movt_r): High halfword 16-bit immediate load
(JSC::ARMAssembler::getImm16Op2): Encode immediate constant for
movw_r and mowt_r

Location:

trunk/JavaScriptCore/assembler

Files:

• ARMAssembler.cpp (modified) (5 diffs)
• ARMAssembler.h (modified) (4 diffs)

trunk/JavaScriptCore/assembler/ARMAssembler.cpp

@@ -119 +119 @@
         return OP2_IMM | (imm >> 24) | (rol << 8);
 
-    return 0;
+    return INVALID_IMM;
 }
 
@@ -237 +237 @@
     // Do it by 1 instruction
     tmp = getOp2(imm);
-    if (tmp)
+    if (tmp != INVALID_IMM)
         return tmp;
 
     tmp = getOp2(~imm);
-    if (tmp) {
+    if (tmp != INVALID_IMM) {
         if (invert)
             return tmp | OP2_INV_IMM;
@@ -248 +248 @@
     }
 
-    // Do it by 2 instruction
-    if (genInt(tmpReg, imm, true))
-        return tmpReg;
-    if (genInt(tmpReg, ~imm, false))
-        return tmpReg;
-
-    ldr_imm(tmpReg, imm);
-    return tmpReg;
+    return encodeComplexImm(imm, tmpReg);
 }
 
@@ -264 +257 @@
     // Do it by 1 instruction
     tmp = getOp2(imm);
-    if (tmp) {
+    if (tmp != INVALID_IMM) {
         mov_r(dest, tmp);
         return;
@@ -270 +263 @@
 
     tmp = getOp2(~imm);
-    if (tmp) {
+    if (tmp != INVALID_IMM) {
         mvn_r(dest, tmp);
         return;
     }
 
+    encodeComplexImm(imm, dest);
+}
+
+ARMWord ARMAssembler::encodeComplexImm(ARMWord imm, int dest)
+{
+    ARMWord tmp;
+
+#if ARM_ARCH_VERSION >= 7
+    tmp = getImm16Op2(imm);
+    if (tmp != INVALID_IMM) {
+        movw_r(dest, tmp);
+        return dest;
+    }
+    movw_r(dest, getImm16Op2(imm & 0xffff));
+    movt_r(dest, getImm16Op2(imm >> 16));
+    return dest;
+#else
     // Do it by 2 instruction
     if (genInt(dest, imm, true))
-        return;
+        return dest;
     if (genInt(dest, ~imm, false))
-        return;
+        return dest;
 
     ldr_imm(dest, imm);
+    return dest;
+#endif
 }
 

trunk/JavaScriptCore/assembler/ARMAssembler.h

@@ -140 +140 @@
             BKPT = 0xe120070,
 #endif
+#if ARM_ARCH_VERSION >= 7
+            MOVW = 0x03000000,
+            MOVT = 0x03400000,
+#endif
         };
 
@@ -176 +180 @@
         };
 
+        static const ARMWord INVALID_IMM = 0xf0000000;
+
         class JmpSrc {
             friend class ARMAssembler;
@@ -334 +340 @@
         }
 
+#if ARM_ARCH_VERSION >= 7
+        void movw_r(int rd, ARMWord op2, Condition cc = AL)
+        {
+            ASSERT((op2 | 0xf0fff) == 0xf0fff);
+            m_buffer.putInt(static_cast<ARMWord>(cc) | MOVW | RD(rd) | op2);
+        }
+
+        void movt_r(int rd, ARMWord op2, Condition cc = AL)
+        {
+            ASSERT((op2 | 0xf0fff) == 0xf0fff);
+            m_buffer.putInt(static_cast<ARMWord>(cc) | MOVT | RD(rd) | op2);
+        }
+#endif
+
         void movs_r(int rd, ARMWord op2, Condition cc = AL)
         {
@@ -709 +729 @@
 
         static ARMWord getOp2(ARMWord imm);
+
+#if ARM_ARCH_VERSION >= 7
+        static ARMWord getImm16Op2(ARMWord imm)
+        {
+            if (imm <= 0xffff)
+                return (imm & 0xf000) << 4 | (imm & 0xfff);
+            return INVALID_IMM;
+        }
+#endif
         ARMWord getImm(ARMWord imm, int tmpReg, bool invert = false);
         void moveImm(ARMWord imm, int dest);
+        ARMWord encodeComplexImm(ARMWord imm, int dest);
 
         // Memory load/store helpers