Fix buggy fcopysign lowering.

This
define float @foo(float %x, float %y) nounwind readnone {
entry:
  %0 = tail call float @copysignf(float %x, float %y) nounwind readnone
  ret float %0
}

Was compiled to:
    vmov     s0, r1
    bic      r0, r0, #-2147483648
    vmov     s1, r0
    vcmpe.f32    s0, #0
    vmrs         apsr_nzcv, fpscr
    it           lt
    vneglt.f32   s1, s1
    vmov         r0, s1
    bx           lr

This fails to copy the sign of -0.0f because it's lost during the float to int
conversion. Also, it's sub-optimal when the inputs are in GPR registers.

Now it uses integer and + or operations when it's profitable. And it's correct!
    lsrs    r1, r1, #31
    bfi     r0, r1, #31, #1
    bx      lr
rdar://8984306

llvm-svn: 125357

1 files changed, 40 insertions, 13 deletions

diff --git a/llvm/test/CodeGen/ARM/fcopysign.ll b/llvm/test/CodeGen/ARM/fcopysign.ll
index a6d741087a8..1050cd26599 100644
--- a/llvm/test/CodeGen/ARM/fcopysign.ll
+++ b/llvm/test/CodeGen/ARM/fcopysign.ll
@@ -1,18 +1,45 @@
-; RUN: llc < %s -march=arm | grep bic | count 2
-; RUN: llc < %s -march=arm -mattr=+v6,+vfp2 | \
-; RUN:   grep vneg | count 2
+; RUN: llc < %s -mtriple=armv7-apple-darwin -mcpu=cortex-a8 | FileCheck %s -check-prefix=SOFT
+; RUN: llc < %s -mtriple=armv7-gnueabi -float-abi=hard -mcpu=cortex-a8 | FileCheck %s -check-prefix=HARD
 
-define float @test1(float %x, double %y) {
-	%tmp = fpext float %x to double
-	%tmp2 = tail call double @copysign( double %tmp, double %y )
-	%tmp3 = fptrunc double %tmp2 to float
-	ret float %tmp3
+; rdar://8984306
+define float @test1(float %x, float %y) nounwind {
+entry:
+; SOFT: test1:
+; SOFT: lsr r1, r1, #31
+; SOFT: bfi r0, r1, #31, #1
+
+; HARD: test1:
+; HARD: vabs.f32 d0, d0
+; HARD: cmp r0, #0
+; HARD: vneglt.f32 s0, s0
+  %0 = tail call float @copysignf(float %x, float %y) nounwind
+  ret float %0
+}
+
+define double @test2(double %x, double %y) nounwind {
+entry:
+; SOFT: test2:
+; SOFT: lsr r2, r3, #31
+; SOFT: bfi r1, r2, #31, #1
+
+; HARD: test2:
+; HARD: vabs.f64 d0, d0
+; HARD: cmp r1, #0
+; HARD: vneglt.f64 d0, d0
+  %0 = tail call double @copysign(double %x, double %y) nounwind
+  ret double %0
 }
 
-define double @test2(double %x, float %y) {
-	%tmp = fpext float %y to double
-	%tmp2 = tail call double @copysign( double %x, double %tmp )
-	ret double %tmp2
+define double @test3(double %x, double %y, double %z) nounwind {
+entry:
+; SOFT: test3:
+; SOFT: vabs.f64
+; SOFT: cmp {{.*}}, #0
+; SOFT: vneglt.f64
+  %0 = fmul double %x, %y
+  %1 = tail call double @copysign(double %0, double %z) nounwind
+  ret double %1
 }
 
-declare double @copysign(double, double)
+declare double @copysign(double, double) nounwind
+declare float @copysignf(float, float) nounwind