[PowerPC] Allow absolute expressions in relocations

The Linux kernel build uses absolute expressions suffixed with @lo/@ha
relocations. This currently doesn't work for DS/DQ form instructions and
there is no reason for it not to. It also works with GAS.
This patch allows this as long as the value is a multiple of 4/16
for DS/DQ form.

Differential revision: https://reviews.llvm.org/D115419

1 files changed, 24 insertions, 39 deletions

diff --git a/llvm/lib/Target/PowerPC/AsmParser/PPCAsmParser.cpp b/llvm/lib/Target/PowerPC/AsmParser/PPCAsmParser.cpp
index 715cff72dcab..7113fe33b5d7 100644
--- a/llvm/lib/Target/PowerPC/AsmParser/PPCAsmParser.cpp
+++ b/llvm/lib/Target/PowerPC/AsmParser/PPCAsmParser.cpp
@@ -341,31 +341,11 @@ public:
 
   bool isU10Imm() const { return Kind == Immediate && isUInt<10>(getImm()); }
   bool isU12Imm() const { return Kind == Immediate && isUInt<12>(getImm()); }
-  bool isU16Imm() const {
-    switch (Kind) {
-      case Expression:
-        return true;
-      case Immediate:
-      case ContextImmediate:
-        return isUInt<16>(getImmU16Context());
-      default:
-        return false;
-    }
-  }
-  bool isS16Imm() const {
-    switch (Kind) {
-      case Expression:
-        return true;
-      case Immediate:
-      case ContextImmediate:
-        return isInt<16>(getImmS16Context());
-      default:
-        return false;
-    }
-  }
-  bool isS16ImmX4() const { return Kind == Expression ||
-                                   (Kind == Immediate && isInt<16>(getImm()) &&
-                                    (getImm() & 3) == 0); }
+  bool isU16Imm() const { return isExtImm<16>(/*Signed*/ false, 1); }
+  bool isS16Imm() const { return isExtImm<16>(/*Signed*/ true, 1); }
+  bool isS16ImmX4() const { return isExtImm<16>(/*Signed*/ true, 4); }
+  bool isS16ImmX16() const { return isExtImm<16>(/*Signed*/ true, 16); }
+  bool isS17Imm() const { return isExtImm<17>(/*Signed*/ true, 1); }
 
   bool isHashImmX8() const {
     // The Hash Imm form is used for instructions that check or store a hash.
@@ -375,9 +355,6 @@ public:
             (getImm() & 7) == 0);
   }
 
-  bool isS16ImmX16() const { return Kind == Expression ||
-                                    (Kind == Immediate && isInt<16>(getImm()) &&
-                                     (getImm() & 15) == 0); }
   bool isS34ImmX16() const {
     return Kind == Expression ||
            (Kind == Immediate && isInt<34>(getImm()) && (getImm() & 15) == 0);
@@ -388,17 +365,6 @@ public:
     return Kind == Expression || (Kind == Immediate && isInt<34>(getImm()));
   }
 
-  bool isS17Imm() const {
-    switch (Kind) {
-      case Expression:
-        return true;
-      case Immediate:
-      case ContextImmediate:
-        return isInt<17>(getImmS16Context());
-      default:
-        return false;
-    }
-  }
   bool isTLSReg() const { return Kind == TLSRegister; }
   bool isDirectBr() const {
     if (Kind == Expression)
@@ -712,6 +678,25 @@ public:
 
     return CreateExpr(Val, S, E, IsPPC64);
   }
+
+private:
+  template <unsigned Width>
+  bool isExtImm(bool Signed, unsigned Multiple) const {
+    switch (Kind) {
+    default:
+      return false;
+    case Expression:
+      return true;
+    case Immediate:
+    case ContextImmediate:
+      if (Signed)
+        return isInt<Width>(getImmS16Context()) &&
+               (getImmS16Context() & (Multiple - 1)) == 0;
+      else
+        return isUInt<Width>(getImmU16Context()) &&
+               (getImmU16Context() & (Multiple - 1)) == 0;
+    }
+  }
 };
 
 } // end anonymous namespace.