Revert "Handle non-power-of-2 divisors in division-like operations", "A64 tweaks for division-like …

src/utils.h

Index: src/utils.h
diff --git a/src/utils.h b/src/utils.h
index 753822614cdac7de30fee972523cc2814509628f..a20e2092612784368bdeae6b39322203bd30dbc5 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -105,6 +105,32 @@ inline int MostSignificantBit(uint32_t x) {
 }
 
 
+// Magic numbers for integer division.
+// These are kind of 2's complement reciprocal of the divisors.
+// Details and proofs can be found in:
+// - Hacker's Delight, Henry S. Warren, Jr.
+// - The PowerPC Compiler Writer’s Guide
+// and probably many others.
+// See details in the implementation of the algorithm in
+// lithium-codegen-arm.cc : LCodeGen::TryEmitSignedIntegerDivisionByConstant().
+struct DivMagicNumbers {
+  unsigned M;
+  unsigned s;
+};
+
+const DivMagicNumbers InvalidDivMagicNumber= {0, 0};
+const DivMagicNumbers DivMagicNumberFor3   = {0x55555556, 0};
+const DivMagicNumbers DivMagicNumberFor5   = {0x66666667, 1};
+const DivMagicNumbers DivMagicNumberFor7   = {0x92492493, 2};
+const DivMagicNumbers DivMagicNumberFor9   = {0x38e38e39, 1};
+const DivMagicNumbers DivMagicNumberFor11  = {0x2e8ba2e9, 1};
+const DivMagicNumbers DivMagicNumberFor25  = {0x51eb851f, 3};
+const DivMagicNumbers DivMagicNumberFor125 = {0x10624dd3, 3};
+const DivMagicNumbers DivMagicNumberFor625 = {0x68db8bad, 8};
+
+const DivMagicNumbers DivMagicNumberFor(int32_t divisor);
+
+
 // The C++ standard leaves the semantics of '>>' undefined for
 // negative signed operands. Most implementations do the right thing,
 // though.