[DAGCombiner] Fix visitSTORE to continue processing current SDNode, if findBetterNeighborChains doesn't actually CombineTo it.

Summary:
findBetterNeighborChains may or may not find a better chain for each node it finds, which include the node ("St") that visitSTORE is currently processing. If no better chain is found for St, visitSTORE should continue instead of return SDValue(St, 0), as if it's CombinedTo'ed.

This fixes bug 28130. There might be other ways to make the test pass (see D21409). I think both of the patches are fixing actual bugs revealed by the same testcase.

Reviewers: echristo, wschmidt, hfinkel, kbarton, amehsan, arsenm, nemanjai, bogner

Subscribers: mehdi_amini, nemanjai, llvm-commits

Differential Revision: http://reviews.llvm.org/D21692

llvm-svn: 274644

1 files changed, 70 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/PowerPC/pr28130.ll b/llvm/test/CodeGen/PowerPC/pr28130.ll
new file mode 100644
index 00000000000..e549c46d956
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/pr28130.ll
@@ -0,0 +1,70 @@
+; RUN: llc -O0 < %s | FileCheck %s
+target triple = "powerpc64le-unknown-linux-gnu"
+
+%StructA = type { double, double, double, double, double, double, double, double }
+
+define void @Test(%StructA* %tmp) unnamed_addr #0 align 2 {
+; CHECK-LABEL: Test:
+; CHECK: lxvd2x
+; CHECK-NEXT: xxswapd
+; CHECK: lxvd2x
+; CHECK-NEXT: xxswapd
+; CHECK: lxvd2x
+; CHECK-NEXT: xxswapd
+; CHECK: lxvd2x
+; CHECK-NEXT: xxswapd
+; CHECK: xxswapd [[OUTPUT:[0-9]+]]
+; CHECK-NEXT: stxvd2x [[OUTPUT]]
+bb:
+  %tmp2 = getelementptr inbounds %StructA, %StructA* %tmp, i64 0, i32 0
+  %tmp4 = bitcast %StructA* %tmp to <2 x double>*
+  %tmp5 = getelementptr inbounds %StructA, %StructA* %tmp, i64 0, i32 2
+  %tmp9 = getelementptr inbounds %StructA, %StructA* %tmp, i64 0, i32 4
+  %tmp11 = getelementptr inbounds %StructA, %StructA* %tmp, i64 0, i32 5
+  %tmp13 = getelementptr inbounds %StructA, %StructA* %tmp, i64 0, i32 6
+  %tmp15 = getelementptr inbounds %StructA, %StructA* %tmp, i64 0, i32 7
+  %tmp18 = load double, double* %tmp2, align 16
+  %tmp19 = load double, double* %tmp11, align 8
+  %tmp20 = load double, double* %tmp9, align 16
+  %tmp21 = fsub double 1.210000e+04, %tmp20
+  %tmp22 = fmul double %tmp18, %tmp21
+  %tmp23 = fadd double %tmp20, %tmp22
+  %tmp24 = load double, double* %tmp13, align 16
+  %tmp25 = fsub double 1.000000e+02, %tmp24
+  %tmp26 = fmul double %tmp18, %tmp25
+  %tmp27 = fadd double %tmp24, %tmp26
+  %tmp28 = load double, double* %tmp15, align 8
+  %tmp29 = insertelement <2 x double> undef, double %tmp19, i32 0
+  %tmp30 = insertelement <2 x double> %tmp29, double %tmp28, i32 1
+  %tmp31 = fsub <2 x double> <double 1.100000e+04, double 1.100000e+02>, %tmp30
+  %tmp32 = insertelement <2 x double> undef, double %tmp18, i32 0
+  %tmp33 = insertelement <2 x double> %tmp32, double %tmp18, i32 1
+  %tmp34 = fmul <2 x double> %tmp33, %tmp31
+  %tmp35 = fadd <2 x double> %tmp30, %tmp34
+  %tmp36 = bitcast double* %tmp5 to <2 x double>*
+  %tmp37 = load <2 x double>, <2 x double>* %tmp36, align 16
+  %tmp38 = fsub <2 x double> <double 1.000000e+00, double 1.000000e+04>, %tmp37
+  %tmp39 = fmul <2 x double> %tmp33, %tmp38
+  %tmp40 = fadd <2 x double> %tmp37, %tmp39
+  %tmp41 = fsub <2 x double> <double 1.000000e+00, double 1.000000e+04>, %tmp40
+  %tmp42 = fmul <2 x double> %tmp33, %tmp41
+  %tmp43 = fadd <2 x double> %tmp40, %tmp42
+  %tmp44 = fsub <2 x double> <double 1.200000e+04, double 1.200000e+02>, %tmp35
+  %tmp45 = fmul <2 x double> %tmp33, %tmp44
+  %tmp46 = fadd <2 x double> %tmp35, %tmp45
+  %tmp48 = fsub double 1.440000e+04, %tmp23
+  %tmp49 = fmul double %tmp18, %tmp48
+  %tmp50 = fadd double %tmp23, %tmp49
+  store double %tmp50, double* %tmp9, align 16
+  %tmp51 = fsub double 1.000000e+02, %tmp27
+  %tmp52 = fmul double %tmp18, %tmp51
+  %tmp53 = fadd double %tmp27, %tmp52
+  store double %tmp53, double* %tmp13, align 16
+  %tmp54 = extractelement <2 x double> %tmp46, i32 1
+  store double %tmp54, double* %tmp15, align 8
+  %tmp55 = bitcast double* %tmp5 to <2 x double>*
+  store <2 x double> %tmp43, <2 x double>* %tmp55, align 16
+  ret void
+}
+
+attributes #0 = { nounwind "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="pwr8" "target-features"="+altivec,+bpermd,+crypto,+direct-move,+extdiv,+power8-vector,+vsx,-qpx" "unsafe-fp-math"="false" "use-soft-float"="false" }