1 files changed, 52 insertions, 0 deletions
diff --git a/test/CodeGen/ARM/subreg-remat.ll b/test/CodeGen/ARM/subreg-remat.ll
new file mode 100644
index 0000000..993d7ec
--- /dev/null
+++ b/test/CodeGen/ARM/subreg-remat.ll
@@ -0,0 +1,52 @@
+; RUN: llc < %s -relocation-model=pic -disable-fp-elim -mcpu=cortex-a8 -pre-RA-sched=source | FileCheck %s
+target triple = "thumbv7-apple-ios"
+; <rdar://problem/10032939>
+;
+; The vector %v2 is built like this:
+;
+;   %vreg6:ssub_1<def> = VMOVSR %vreg0<kill>, pred:14, pred:%noreg, %vreg6<imp-def>; DPR_VFP2:%vreg6 GPR:%vreg0
+;   %vreg6:ssub_0<def> = VLDRS <cp#0>, 0, pred:14, pred:%noreg; mem:LD4[ConstantPool] DPR_VFP2:%vreg6
+;
+; When %vreg6 spills, the VLDRS constant pool load cannot be rematerialized
+; since it implicitly reads the ssub_1 sub-register.
+;
+; CHECK: f1
+; CHECK: vmov    s1, r0
+; CHECK: vldr.32 s0, LCPI
+; The vector must be spilled:
+; CHECK: vstr.64 d0,
+; CHECK: asm clobber d0
+; And reloaded after the asm:
+; CHECK: vldr.64 [[D16:d[0-9]+]],
+; CHECK: vstr.64 [[D16]], [r1]
+define void @f1(float %x, <2 x float>* %p) {
+  %v1 = insertelement <2 x float> undef, float %x, i32 1
+  %v2 = insertelement <2 x float> %v1, float 0x400921FB60000000, i32 0
+  %y = call double asm sideeffect "asm clobber $0", "=w,0,~{d1},~{d2},~{d3},~{d4},~{d5},~{d6},~{d7},~{d8},~{d9},~{d10},~{d11},~{d12},~{d13},~{d14},~{d15},~{d16},~{d17},~{d18},~{d19},~{d20},~{d21},~{d22},~{d23},~{d24},~{d25},~{d26},~{d27},~{d28},~{d29},~{d30},~{d31}"(<2 x float> %v2) nounwind
+  store <2 x float> %v2, <2 x float>* %p, align 8
+  ret void
+}
+
+; On the other hand, when the partial redef doesn't read the full register
+; because the bits are undef, we should rematerialize.  The vector is now built
+; like this:
+;
+;   %vreg2:ssub_0<def> = VLDRS <cp#0>, 0, pred:14, pred:%noreg, %vreg2<imp-def>; mem:LD4[ConstantPool]
+;
+; The extra <imp-def> operand indicates that the instruction fully defines the
+; virtual register.  It doesn't read the old value.
+;
+; CHECK: f2
+; CHECK: vldr.32 s0, LCPI
+; The vector must not be spilled:
+; CHECK-NOT: vstr.64
+; CHECK: asm clobber d0
+; But instead rematerialize after the asm:
+; CHECK: vldr.32 [[S0:s[0-9]+]], LCPI
+; CHECK: vstr.64 [[D0:d[0-9]+]], [r0]
+define void @f2(<2 x float>* %p) {
+  %v2 = insertelement <2 x float> undef, float 0x400921FB60000000, i32 0
+  %y = call double asm sideeffect "asm clobber $0", "=w,0,~{d1},~{d2},~{d3},~{d4},~{d5},~{d6},~{d7},~{d8},~{d9},~{d10},~{d11},~{d12},~{d13},~{d14},~{d15},~{d16},~{d17},~{d18},~{d19},~{d20},~{d21},~{d22},~{d23},~{d24},~{d25},~{d26},~{d27},~{d28},~{d29},~{d30},~{d31}"(<2 x float> %v2) nounwind
+  store <2 x float> %v2, <2 x float>* %p, align 8
+  ret void
+}