Add the first backend support for on demand subtarget creation

based on the Function. This is currently used to implement
mips16 support in the mips backend via the existing module
pass resetting the subtarget.

Things to note:

a) This involved running resetTargetOptions before creating a
new subtarget so that code generation options like soft-float
could be recognized when creating the new subtarget. This is
to deal with initialization code in isel lowering that only
paid attention to the initial value.

b) Many of the existing testcases weren't using the soft-float
feature correctly. I've corrected these based on the check
values assuming that was the desired behavior.

c) The mips port now pays attention to the target-cpu and
target-features strings when generating code for a particular
function. I've removed these from one function where the
requested cpu and features didn't match the check lines in
the testcase.

llvm-svn: 218492

1 files changed, 41 insertions, 13 deletions

diff --git a/llvm/lib/Target/Mips/MipsTargetMachine.cpp b/llvm/lib/Target/Mips/MipsTargetMachine.cpp
index 79d1b4b..afa60d2 100644
--- a/llvm/lib/Target/Mips/MipsTargetMachine.cpp
+++ b/llvm/lib/Target/Mips/MipsTargetMachine.cpp
@@ -56,7 +56,8 @@ MipsTargetMachine::MipsTargetMachine(const Target &T, StringRef TT,
                                      Reloc::Model RM, CodeModel::Model CM,
                                      CodeGenOpt::Level OL, bool isLittle)
     : LLVMTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL),
-      Subtarget(nullptr), DefaultSubtarget(TT, CPU, FS, isLittle, this),
+      isLittle(isLittle), Subtarget(nullptr),
+      DefaultSubtarget(TT, CPU, FS, isLittle, this),
       NoMips16Subtarget(TT, CPU, FS.empty() ? "-mips16" : FS.str() + ",-mips16",
                         isLittle, this),
       Mips16Subtarget(TT, CPU, FS.empty() ? "+mips16" : FS.str() + ",+mips16",
@@ -83,20 +84,47 @@ MipselTargetMachine(const Target &T, StringRef TT,
                     CodeGenOpt::Level OL)
   : MipsTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, true) {}
 
+const MipsSubtarget *
+MipsTargetMachine::getSubtargetImpl(const Function &F) const override {
+  AttributeSet FnAttrs = F.getAttributes();
+  Attribute CPUAttr =
+      FnAttrs.getAttribute(AttributeSet::FunctionIndex, "target-cpu");
+  Attribute FSAttr =
+      FnAttrs.getAttribute(AttributeSet::FunctionIndex, "target-features");
+
+  std::string CPU = !CPUAttr.hasAttribute(Attribute::None)
+                        ? CPUAttr.getValueAsString().str()
+                        : TargetCPU;
+  std::string FS = !FSAttr.hasAttribute(Attribute::None)
+                       ? FSAttr.getValueAsString().str()
+                       : TargetFS;
+  bool hasMips16Attr =
+      !FnAttrs.getAttribute(AttributeSet::FunctionIndex, "mips16")
+           .hasAttribute(Attribute::None);
+  bool hasNoMips16Attr =
+      !FnAttrs.getAttribute(AttributeSet::FunctionIndex, "nomips16")
+           .hasAttribute(Attribute::None);
+
+  if (hasMips16Attr)
+    FS += FS.empty() ? "+mips16" : ",+mips16";
+  else if (hasNoMips16Attr)
+    FS += FS.empty() ? "-mips16" : ",-mips16";
+
+  auto &I = SubtargetMap[CPU + FS];
+  if (!I) {
+    // This needs to be done before we create a new subtarget since any
+    // creation will depend on the TM and the code generation flags on the
+    // function that reside in TargetOptions.
+    resetTargetOptions(F);
+    I = make_unique<MipsSubtarget>(TargetTriple, CPU, FS, isLittle, this);
+  }
+  return I.get();
+}
+
 void MipsTargetMachine::resetSubtarget(MachineFunction *MF) {
   DEBUG(dbgs() << "resetSubtarget\n");
-  AttributeSet FnAttrs = MF->getFunction()->getAttributes();
-  bool Mips16Attr = FnAttrs.hasAttribute(AttributeSet::FunctionIndex, "mips16");
-  bool NoMips16Attr =
-      FnAttrs.hasAttribute(AttributeSet::FunctionIndex, "nomips16");
-  assert(!(Mips16Attr && NoMips16Attr) &&
-         "mips16 and nomips16 specified on the same function");
-  if (Mips16Attr)
-    Subtarget = &Mips16Subtarget;
-  else if (NoMips16Attr)
-    Subtarget = &NoMips16Subtarget;
-  else
-    Subtarget = &DefaultSubtarget;
+
+  Subtarget = const_cast<MipsSubtarget*>(getSubtargetImpl(MF->getFunction()));
   MF->setSubtarget(Subtarget);
   return;
 }