// Handle the floating point versions of equality comparisons too.
if ((isKnownTrue && Cmp->getPredicate() == CmpInst::FCMP_OEQ) ||
(isKnownFalse && Cmp->getPredicate() == CmpInst::FCMP_UNE)) {
- // Floating point -0.0 and 0.0 compare equal, so we can't
- // propagate a constant based on that comparison.
+
+ // Floating point -0.0 and 0.0 compare equal, so we can only
+ // propagate values if we know that we have a constant and that
+ // its value is non-zero.
+
// FIXME: We should do this optimization if 'no signed zeros' is
// applicable via an instruction-level fast-math-flag or some other
// indicator that relaxed FP semantics are being used.
- if (!isa<ConstantFP>(Op1) || !cast<ConstantFP>(Op1)->isZero())
+
+ if (isa<ConstantFP>(Op1) && !cast<ConstantFP>(Op1)->isZero())
Worklist.push_back(std::make_pair(Op0, Op1));
}
ret void
}
-define double @fcmp_oeq(double %x, double %y) {
+define double @fcmp_oeq_not_zero(double %x, double %y) {
entry:
%cmp = fcmp oeq double %y, 2.0
br i1 %cmp, label %if, label %return
%retval = phi double [ %div, %if ], [ %x, %entry ]
ret double %retval
-; CHECK-LABEL: define double @fcmp_oeq(
+; CHECK-LABEL: define double @fcmp_oeq_not_zero(
; CHECK: %div = fdiv double %x, 2.0
}
-define double @fcmp_une(double %x, double %y) {
+define double @fcmp_une_not_zero(double %x, double %y) {
entry:
%cmp = fcmp une double %y, 2.0
br i1 %cmp, label %return, label %else
%retval = phi double [ %div, %else ], [ %x, %entry ]
ret double %retval
-; CHECK-LABEL: define double @fcmp_une(
+; CHECK-LABEL: define double @fcmp_une_not_zero(
; CHECK: %div = fdiv double %x, 2.0
}
; CHECK-LABEL: define double @fcmp_une_zero(
; CHECK: %div = fdiv double %x, %y
}
+
+; We also cannot propagate a value if it's not a constant.
+; This is because the value could be 0.0 or -0.0.
+
+define double @fcmp_oeq_maybe_zero(double %x, double %y, double %z1, double %z2) {
+entry:
+ %z = fadd double %z1, %z2
+ %cmp = fcmp oeq double %y, %z
+ br i1 %cmp, label %if, label %return
+
+if:
+ %div = fdiv double %x, %z
+ br label %return
+
+return:
+ %retval = phi double [ %div, %if ], [ %x, %entry ]
+ ret double %retval
+
+; CHECK-LABEL: define double @fcmp_oeq_maybe_zero(
+; CHECK: %div = fdiv double %x, %z
+}
+
+define double @fcmp_une_maybe_zero(double %x, double %y, double %z1, double %z2) {
+entry:
+ %z = fadd double %z1, %z2
+ %cmp = fcmp une double %y, %z
+ br i1 %cmp, label %return, label %else
+
+else:
+ %div = fdiv double %x, %z
+ br label %return
+
+return:
+ %retval = phi double [ %div, %else ], [ %x, %entry ]
+ ret double %retval
+
+; CHECK-LABEL: define double @fcmp_une_maybe_zero(
+; CHECK: %div = fdiv double %x, %z
+}