Allow Sparc back-end to take the address of a function (or other global object)

[lero_chris]

Summary

The following code would not work before this patch, due to the inability to take the address of a global object:

void func1() {

...

}

int main(int argc, char** argv) {

void (*pFunc)();
pFunc = &func1
pFunc();
...

}

[jacob_hansen]

This looks good for me (not sure I can formally accept it as I do not yet have SVN write access though).

[lero_chris]

Unit tests to go with this change.

lib/Target/Sparc/DelaySlotFiller.cpp

void Filler::insertCallDefsUses(MachineBasicBlock::iterator MI,
   case SP::CALLrr:
   case SP::CALLri:
     assert(MI->getNumOperands() >= 2);
     const MachineOperand &Reg = MI->getOperand(0);
     assert(Reg.isReg() && "CALL first operand is not a register.");
     assert(Reg.isUse() && "CALL first operand is not a use.");
     RegUses.insert(Reg.getReg());
 
-    const MachineOperand &RegOrImm = MI->getOperand(1);
-    if (RegOrImm.isImm() || RegOrImm.isGlobal())
+    const MachineOperand &Operand1 = MI->getOperand(1);
+    if (Operand1.isImm() || Operand1.isGlobal())
         break;
-    assert(RegOrImm.isReg() && "CALLrr second operand is not a register.");
-    assert(RegOrImm.isUse() && "CALLrr second operand is not a use.");
-    RegUses.insert(RegOrImm.getReg());
+    assert(Operand1.isReg() && "CALLrr second operand is not a register.");
+    assert(Operand1.isUse() && "CALLrr second operand is not a use.");
+    RegUses.insert(Operand1.getReg());
     break;
   }
 }
 
 // Insert Defs and Uses of MI into the sets RegDefs and RegUses.
 void Filler::insertDefsUses(MachineBasicBlock::iterator MI,
                             SmallSet<unsigned, 32>& RegDefs,
                             SmallSet<unsigned, 32>& RegUses)

test/CodeGen/SPARC/func-addr.ll

+; RUN: llc < %s -march=sparc   -relocation-model=static -code-model=small  | FileCheck --check-prefix=abs32 %s
+; RUN: llc < %s -march=sparcv9 -relocation-model=static -code-model=small  | FileCheck --check-prefix=abs32 %s
+; RUN: llc < %s -march=sparcv9 -relocation-model=static -code-model=medium | FileCheck --check-prefix=abs44 %s
+; RUN: llc < %s -march=sparcv9 -relocation-model=static -code-model=large  | FileCheck --check-prefix=abs64 %s
+; RUN: llc < %s -march=sparc   -relocation-model=pic    -code-model=medium | FileCheck --check-prefix=v8pic32 %s
+; RUN: llc < %s -march=sparcv9 -relocation-model=pic    -code-model=medium | FileCheck --check-prefix=v9pic32 %s
+
+define void @func1() #0 {
+entry:
+  ret void
+}
+
+define void @test() #0 {
+entry:
+  %pFunc = alloca void (...)*, align 4
+  store void (...)* bitcast (void ()* @func1 to void (...)*), void (...)** %pFunc, align 4
+  %0 = load void (...)*, void (...)** %pFunc, align 4
+  %callee.knr.cast = bitcast void (...)* %0 to void ()*
+  call void %callee.knr.cast()
+
+; abs32-LABEL:   test
+; abs32:          sethi %hi(func1), %i0
+; abs32:          add %i0, %lo(func1), %i1
+; abs32:          call %i0+%lo(func1)
+
+; abs44-LABEL:   test
+; abs44:          sethi %h44(func1), %i0
+; abs44:          add %i0, %m44(func1), %i0
+; abs44:          sllx %i0, 12, %i0
+; abs44:          add %i0, %l44(func1), %i1
+; abs44:          call %i0+%l44(func1)
+
+; abs64-LABEL:   test
+; abs64:          sethi %hi(func1), %i0
+; abs64:          add %i0, %lo(func1), %i0
+; abs64:          sethi %hh(func1), %i1
+; abs64:          add %i1, %hm(func1), %i1
+
+; v8pic32-LABEL: test
+; v8pic32:        sethi %hi(func1), %i1
+; v8pic32:        add %i1, %lo(func1), %i1
+; v8pic32:        ld [%i0+%i1], %i0
+
+; v9pic32-LABEL: test
+; v9pic32:        sethi %hi(func1), %i1
+; v9pic32:        add %i1, %lo(func1), %i1
+; v9pic32:        ldx [%i0+%i1], %i0
+; v9pic32:        call %i0
+
+  ret void
+}