[PPC] When restoring R30 (PIC base pointer), mark it as <def>

This happened on the PPC32/SVR4 path and was discovered when building
FreeBSD on PPC32. It was a typo-class error in the frame lowering code.

This fixes PR26519.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302183 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/PowerPC/PPCFrameLowering.cpp

@@ -1459,8 +1459,7 @@ void PPCFrameLowering::emitEpilogue(MachineFunction &MF,
   }
 
   if (FI->usesPICBase())
-    BuildMI(MBB, MBBI, dl, LoadInst)
-      .addReg(PPC::R30)
+    BuildMI(MBB, MBBI, dl, LoadInst, PPC::R30)
       .addImm(PBPOffset)
       .addReg(RBReg);
 

test/CodeGen/PowerPC/restore-r30.ll

@@ -0,0 +1,30 @@
+; RUN: llc -march=ppc32 -relocation-model=pic < %s | FileCheck %s
+
+; The load restoring r30 at the end of the function was placed out of order
+; relative to its uses as the PIC base pointer.
+; This was because the r30 operand was not marked as "def" which allowed
+; the post-RA scheduler to move it over other uses of r30.
+
+; CHECK-LABEL: fred
+; CHECK:       lwz 30, 24(1)
+; R30 should not appear in an instruction after it's been restored.
+; CHECK-NOT:   30,
+
+target datalayout = "E-m:e-p:32:32-i64:64-n32"
+target triple = "powerpc"
+
+define double @fred(i64 %a) #0 {
+entry:
+  %0 = lshr i64 %a, 32
+  %conv = trunc i64 %0 to i32
+  %conv1 = sitofp i32 %conv to double
+  %mul = fmul double %conv1, 0x41F0000000000000
+  %and = and i64 %a, 4294967295
+  %or = or i64 %and, 4841369599423283200
+  %sub = fadd double %mul, 0xC330000000000000
+  %1 = bitcast i64 %or to double
+  %add = fadd double %sub, %1
+  ret double %add
+}
+
+attributes #0 = { norecurse nounwind readnone "target-cpu"="ppc" "use-soft-float"="false" }