[llvm] 398df66 - [JITLink][AArch64] Implement MoveWide16 generic edge.

[Sunho Kim via llvm-commits]

Author: Sunho Kim
Date: 2022-06-14T13:51:47+09:00
New Revision: 398df667d6d1d8c0c60bca3a9c6e8ff1419ff958

URL: https://github.com/llvm/llvm-project/commit/398df667d6d1d8c0c60bca3a9c6e8ff1419ff958
DIFF: https://github.com/llvm/llvm-project/commit/398df667d6d1d8c0c60bca3a9c6e8ff1419ff958.diff

LOG: [JITLink][AArch64] Implement MoveWide16 generic edge.

Implements MoveWide16 generic edge kind that can be used to patch MOVZ/MOVK (imm16) instructions.

Reviewed By: lhames

Differential Revision: https://reviews.llvm.org/D127584

Added: 
    

Modified: 
    llvm/include/llvm/ExecutionEngine/JITLink/aarch64.h
    llvm/lib/ExecutionEngine/JITLink/aarch64.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/ExecutionEngine/JITLink/aarch64.h b/llvm/include/llvm/ExecutionEngine/JITLink/aarch64.h
index 2cebc03310e17..42a01c25de146 100644
--- a/llvm/include/llvm/ExecutionEngine/JITLink/aarch64.h
+++ b/llvm/include/llvm/ExecutionEngine/JITLink/aarch64.h
@@ -28,6 +28,7 @@ enum EdgeKind_aarch64 : Edge::Kind {
   Pointer64Anon,
   Page21,
   PageOffset12,
+  MoveWide16,
   GOTPage21,
   GOTPageOffset12,
   TLVPage21,
@@ -72,6 +73,25 @@ inline unsigned getPageOffset12Shift(uint32_t Instr) {
   return 0;
 }
 
+// Returns whether the Instr is MOVK/MOVZ (imm16) with a zero immediate field
+inline bool isMoveWideImm16(uint32_t Instr) {
+  constexpr uint32_t MoveWideImm16Mask = 0x5f9fffe0;
+  return (Instr & MoveWideImm16Mask) == 0x52800000;
+}
+
+// Returns the amount the address operand of MOVK/MOVZ (imm16)
+// should be shifted right by.
+//
+// The shift value is specfied in the assembly as LSL #<shift>.
+inline unsigned getMoveWide16Shift(uint32_t Instr) {
+  if (isMoveWideImm16(Instr)) {
+    uint32_t ImplicitShift = (Instr >> 21) & 0b11;
+    return ImplicitShift << 4;
+  }
+
+  return 0;
+}
+
 /// Apply fixup expression for edge to block content.
 inline Error applyFixup(LinkGraph &G, Block &B, const Edge &E) {
   using namespace support;
@@ -152,6 +172,20 @@ inline Error applyFixup(LinkGraph &G, Block &B, const Edge &E) {
     *(ulittle32_t *)FixupPtr = FixedInstr;
     break;
   }
+  case MoveWide16: {
+    uint64_t TargetOffset =
+        (E.getTarget().getAddress() + E.getAddend()).getValue();
+
+    uint32_t RawInstr = *(ulittle32_t *)FixupPtr;
+    assert(isMoveWideImm16(RawInstr) &&
+           "RawInstr isn't a MOVK/MOVZ instruction");
+
+    unsigned ImmShift = getMoveWide16Shift(RawInstr);
+    uint32_t Imm = (TargetOffset >> ImmShift) & 0xffff;
+    uint32_t FixedInstr = RawInstr | (Imm << 5);
+    *(ulittle32_t *)FixupPtr = FixedInstr;
+    break;
+  }
   case LDRLiteral19: {
     assert((FixupAddress.getValue() & 0x3) == 0 && "LDR is not 32-bit aligned");
     assert(E.getAddend() == 0 && "LDRLiteral19 with non-zero addend");

diff  --git a/llvm/lib/ExecutionEngine/JITLink/aarch64.cpp b/llvm/lib/ExecutionEngine/JITLink/aarch64.cpp
index 1397a45df4c2f..28a6f9ce90d92 100644
--- a/llvm/lib/ExecutionEngine/JITLink/aarch64.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/aarch64.cpp
@@ -38,6 +38,8 @@ const char *getEdgeKindName(Edge::Kind R) {
     return "Page21";
   case PageOffset12:
     return "PageOffset12";
+  case MoveWide16:
+    return "MoveWide16";
   case GOTPage21:
     return "GOTPage21";
   case GOTPageOffset12: