Tmp2 = ComputeNumSignBits(U->getOperand(1), TD, Depth+1);
if (Tmp2 == 1) return 1;
- return std::min(Tmp, Tmp2)-1;
- break;
+ return std::min(Tmp, Tmp2)-1;
case Instruction::Sub:
Tmp2 = ComputeNumSignBits(U->getOperand(1), TD, Depth+1);
// is, at worst, one more bit than the inputs.
Tmp = ComputeNumSignBits(U->getOperand(0), TD, Depth+1);
if (Tmp == 1) return 1; // Early out.
- return std::min(Tmp, Tmp2)-1;
- break;
+ return std::min(Tmp, Tmp2)-1;
+
+ case Instruction::PHI: {
+ PHINode *PN = cast<PHINode>(U);
+ // Don't analyze large in-degree PHIs.
+ if (PN->getNumIncomingValues() > 4) break;
+
+ // Take the minimum of all incoming values. This can't infinitely loop
+ // because of our depth threshold.
+ Tmp = ComputeNumSignBits(PN->getIncomingValue(0), TD, Depth+1);
+ for (unsigned i = 1, e = PN->getNumIncomingValues(); i != e; ++i) {
+ if (Tmp == 1) return Tmp;
+ Tmp = std::min(Tmp,
+ ComputeNumSignBits(PN->getIncomingValue(1), TD, Depth+1));
+ }
+ return Tmp;
+ }
+
case Instruction::Trunc:
// FIXME: it's tricky to do anything useful for this, but it is an important
// case for targets like X86.
; CHECK: @test2
; CHECK: lshr i32 %tmp4, 3
}
+
+define i64 @test3(i1 %X, i64 %Y, i1 %Cond) {
+ br i1 %Cond, label %T, label %F
+T:
+ %X2 = sext i1 %X to i64
+ br label %C
+F:
+ %Y2 = ashr i64 %Y, 63
+ br label %C
+C:
+ %P = phi i64 [%X2, %T], [%Y2, %F]
+ %S = ashr i64 %P, 12
+ ret i64 %S
+
+; CHECK: @test3
+; CHECK: %P = phi i64
+; CHECK-NEXT: ret i64 %P
+}