if (N0CFP && N1CFP && VT != MVT::ppcf128)
return DAG.getNode(ISD::FDIV, N->getDebugLoc(), VT, N0, N1);
+ // fold (fdiv X, c2) -> fmul X, 1/c2 if there is no precision loss or if
+ // losing precision is acceptable.
+ if (N1CFP && VT != MVT::ppcf128) {
+ // Compute the reciprocal 1.0 / c2.
+ APFloat N1APF = N1CFP->getValueAPF();
+ APFloat Recip(N1APF.getSemantics(), 1); // 1.0
+ APFloat::opStatus st = Recip.divide(N1APF, APFloat::rmNearestTiesToEven);
+ // Only do the transform if the reciprocal is not too horrible (eg not NaN).
+ if (st == APFloat::opOK || (st == APFloat::opInexact &&
+ DAG.getTarget().Options.UnsafeFPMath))
+ return DAG.getNode(ISD::FMUL, N->getDebugLoc(), VT, N0,
+ DAG.getConstantFP(Recip, VT));
+ }
// (fdiv (fneg X), (fneg Y)) -> (fdiv X, Y)
if (char LHSNeg = isNegatibleForFree(N0, LegalOperations, TLI,
; Test signed conversion.
; CHECK: t1
-; CHECK-NOT: vdiv
+; CHECK-NOT: {{vdiv|vmul}}
define void @t1() nounwind {
entry:
%tmp = load i32* @iin, align 4, !tbaa !3
; Test unsigned conversion.
; CHECK: t2
-; CHECK-NOT: vdiv
+; CHECK-NOT: {{vdiv|vmul}}
define void @t2() nounwind {
entry:
%tmp = load i32* @uin, align 4, !tbaa !3
; Test which should not fold due to non-power of 2.
; CHECK: t3
-; CHECK: vdiv
+; CHECK: {{vdiv|vmul}}
define void @t3() nounwind {
entry:
%tmp = load i32* @iin, align 4, !tbaa !3
; Test which should not fold due to power of 2 out of range.
; CHECK: t4
-; CHECK: vdiv
+; CHECK: {{vdiv|vmul}}
define void @t4() nounwind {
entry:
%tmp = load i32* @iin, align 4, !tbaa !3
; Test case where const is max power of 2 (i.e., 2^32).
; CHECK: t5
-; CHECK-NOT: vdiv
+; CHECK-NOT: {{vdiv|vmul}}
define void @t5() nounwind {
entry:
%tmp = load i32* @iin, align 4, !tbaa !3
; Test quadword.
; CHECK: t6
-; CHECK-NOT: vdiv
+; CHECK-NOT: {{vdiv|vmul}}
define void @t6() nounwind {
entry:
%tmp = load i32* @iin, align 4, !tbaa !3
--- /dev/null
+; RUN: llc < %s -march=x86-64 | FileCheck %s
+; RUN: llc < %s -march=x86-64 -enable-unsafe-fp-math | FileCheck -check-prefix=UNSAFE %s
+
+define double @exact(double %x) {
+; Exact division by a constant always converted to multiplication.
+; CHECK: @exact
+; CHECK: mulsd
+; UNSAFE: @exact
+; UNSAFE: mulsd
+ %div = fdiv double %x, 2.0
+ ret double %div
+}
+
+define double @inexact(double %x) {
+; Inexact division by a constant converted to multiplication if unsafe-math.
+; CHECK: @inexact
+; CHECK: divsd
+; UNSAFE: @inexact
+; UNSAFE: mulsd
+ %div = fdiv double %x, 0x41DFFFFFFFC00000
+ ret double %div
+}
+
+define double @funky(double %x) {
+; No conversion to multiplication if too funky.
+; CHECK: @funky
+; CHECK: divsd
+; UNSAFE: @funky
+; UNSAFE: divsd
+ %div = fdiv double %x, 0.0
+ ret double %div
+}