[SPARC] Fix BooleanContents, so that select of a trunc doesn't

eliminate the trunc.

Differential Revision: http://reviews.llvm.org/D10442

llvm-svn: 245444

lib/Target/Sparc/SparcISelLowering.cpp

@@ -1423,6 +1423,14 @@ SparcTargetLowering::SparcTargetLowering(TargetMachine &TM,
     : TargetLowering(TM), Subtarget(&STI) {
   MVT PtrVT = MVT::getIntegerVT(8 * TM.getPointerSize());
 
+  // Instructions which use registers as conditionals examine all the
+  // bits (as does the pseudo SELECT_CC expansion). I don't think it
+  // matters much whether it's ZeroOrOneBooleanContent, or
+  // ZeroOrNegativeOneBooleanContent, so, arbitrarily choose the
+  // former.
+  setBooleanContents(ZeroOrOneBooleanContent);
+  setBooleanVectorContents(ZeroOrOneBooleanContent);
+
   // Set up the register classes.
   addRegisterClass(MVT::i32, &SP::IntRegsRegClass);
   addRegisterClass(MVT::f32, &SP::FPRegsRegClass);

test/CodeGen/SPARC/select-mask.ll

@@ -0,0 +1,17 @@
+; RUN: llc -march=sparc < %s
+
+;; getBooleanContents on Sparc used to claim that no bits mattered
+;; other than the first for SELECT. Thus, the 'trunc' got eliminated
+;; as redundant. But, cmp does NOT ignore the other bits!
+
+; CHECK-LABEL select_mask:
+; CHECK: ldub [%o0], [[R:%[goli][0-7]]]
+; CHECK: and [[R]], 1, [[V:%[goli][0-7]]]
+; CHECK: cmp [[V]], 0
+define i32 @select_mask(i8* %this) {
+entry:
+  %bf.load2 = load i8, i8* %this, align 4
+  %bf.cast5 = trunc i8 %bf.load2 to i1
+  %cond = select i1 %bf.cast5, i32 2, i32 0
+  ret i32 %cond
+}