[mips] Make it impossible to have UnknownABI in CodeGen and Integrated Assembler.

Summary:
This removes the need to coerce UnknownABI to the default ABI (O32 for
MIPS32, N64 for MIPS64 [*]) in both MipsSubtarget and MipsAsmParser.

Clang has been updated to disable both possible default ABI's before enabling
the ABI it intends to use.

[*] N64 being the default for MIPS64 is not actually correct.
    However N32 is not fully implemented/tested yet.

Depends on: D2830

Reviewers: jacksprat, matheusalmeida

Reviewed By: matheusalmeida

Differential Revision: http://llvm-reviews.chandlerc.com/D2832
Differential Revision: http://llvm-reviews.chandlerc.com/D2846

llvm-svn: 201792

3 files changed, 17 insertions, 8 deletions

diff --git a/llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp b/llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
index e99de130779..378235e1aaf 100644
--- a/llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
+++ b/llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp
@@ -264,6 +264,12 @@ public:
         hasConsumedDollar(false) {
     // Initialize the set of available features.
     setAvailableFeatures(ComputeAvailableFeatures(STI.getFeatureBits()));
+
+    // Assert exactly one ABI was chosen.
+    assert((((STI.getFeatureBits() & Mips::FeatureO32) != 0) +
+            ((STI.getFeatureBits() & Mips::FeatureEABI) != 0) +
+            ((STI.getFeatureBits() & Mips::FeatureN32) != 0) +
+            ((STI.getFeatureBits() & Mips::FeatureN64) != 0)) == 1);
   }
 
   MCAsmParser &getParser() const { return Parser; }
diff --git a/llvm/lib/Target/Mips/Mips.td b/llvm/lib/Target/Mips/Mips.td
index c7ebdac1c05..a9e8dca80b4 100644
--- a/llvm/lib/Target/Mips/Mips.td
+++ b/llvm/lib/Target/Mips/Mips.td
@@ -90,11 +90,11 @@ def FeatureMicroMips  : SubtargetFeature<"micromips", "InMicroMipsMode", "true",
 class Proc<string Name, list<SubtargetFeature> Features>
  : Processor<Name, MipsGenericItineraries, Features>;
 
-def : Proc<"mips32", [FeatureMips32]>;
-def : Proc<"mips32r2", [FeatureMips32r2]>;
-def : Proc<"mips64", [FeatureMips64]>;
-def : Proc<"mips64r2", [FeatureMips64r2]>;
-def : Proc<"mips16", [FeatureMips16]>;
+def : Proc<"mips32", [FeatureMips32, FeatureO32]>;
+def : Proc<"mips32r2", [FeatureMips32r2, FeatureO32]>;
+def : Proc<"mips64", [FeatureMips64, FeatureN64]>;
+def : Proc<"mips64r2", [FeatureMips64r2, FeatureN64]>;
+def : Proc<"mips16", [FeatureMips16, FeatureO32]>;
 
 def MipsAsmParser : AsmParser {
   let ShouldEmitMatchRegisterName = 0;
diff --git a/llvm/lib/Target/Mips/MipsSubtarget.cpp b/llvm/lib/Target/Mips/MipsSubtarget.cpp
index a5d910e3e5d..f16fb798286 100644
--- a/llvm/lib/Target/Mips/MipsSubtarget.cpp
+++ b/llvm/lib/Target/Mips/MipsSubtarget.cpp
@@ -109,9 +109,12 @@ MipsSubtarget::MipsSubtarget(const std::string &TT, const std::string &CPU,
   // Initialize scheduling itinerary for the specified CPU.
   InstrItins = getInstrItineraryForCPU(CPUName);
 
-  // Set MipsABI if it hasn't been set yet.
-  if (MipsABI == UnknownABI)
-    MipsABI = hasMips64() ? N64 : O32;
+  // Assert exactly one ABI was chosen.
+  assert(MipsABI != UnknownABI);
+  assert((((getFeatureBits() & Mips::FeatureO32) != 0) +
+          ((getFeatureBits() & Mips::FeatureEABI) != 0) +
+          ((getFeatureBits() & Mips::FeatureN32) != 0) +
+          ((getFeatureBits() & Mips::FeatureN64) != 0)) == 1);
 
   // Check if Architecture and ABI are compatible.
   assert(((!hasMips64() && (isABI_O32() || isABI_EABI())) ||