[PowerPC] Fix PR16556 (handle undef ppcf128 in LowerFP_TO_INT).

PPCTargetLowering::LowerFP_TO_INT() expects its source operand to be
either an f32 or f64, but this is not checked.  A long double
(ppcf128) operand will normally be custom-lowered to a conversion to
f64 in this context.  However, this isn't the case for an UNDEF node.

This patch recognizes a ppcf128 as a legal source operand for
FP_TO_INT only if it's an undef, in which case it creates an undef of
the target type.

At some point we might want to do a wholesale custom lowering of
ISD::UNDEF when the type is ppcf128, but it's not really clear that's
a great idea, and probably more work than it's worth for a situation
that only arises in the case of a programming error.  At this point I
think simple is best.

The test case comes from PR16556, and is a crash-test only.

llvm-svn: 185821

1 files changed, 20 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/PowerPC/pr16556.ll b/llvm/test/CodeGen/PowerPC/pr16556.ll
new file mode 100644
index 00000000000..dc36f0b6eaf
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/pr16556.ll
@@ -0,0 +1,20 @@
+; RUN: llc < %s
+
+; This test formerly failed due to no handling for a ppc_fp128 undef.
+
+target datalayout = "E-p:32:32:32-S0-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f16:16:16-f32:32:32-f64:64:64-f128:64:128-v64:64:64-v128:128:128-a0:0:64-n32"
+target triple = "powerpc-unknown-linux-gnu"
+
+%core.time.TickDuration.37.125 = type { i64 }
+
+define weak_odr fastcc i64 @_D4core4time12TickDuration30__T2toVAyaa7_7365636f6e6473TlZ2toMxFNaNbNfZl(%core.time.TickDuration.37.125* %.this_arg) {
+entry:
+  br i1 undef, label %noassert, label %assert
+
+assert:                                           ; preds = %entry
+  unreachable
+
+noassert:                                         ; preds = %entry
+  %tmp9 = fptosi ppc_fp128 undef to i64
+  ret i64 %tmp9
+}