[ARM GlobalISel] Support G_CTLZ and G_CTLZ_ZERO_UNDEF
We can now select CLZ via the TableGen'erated code, so support G_CTLZ
and G_CTLZ_ZERO_UNDEF throughout the pipeline for types <= s32.
Legalizer:
If the CLZ instruction is available, use it for both G_CTLZ and
G_CTLZ_ZERO_UNDEF. Otherwise, use a libcall for G_CTLZ_ZERO_UNDEF and
lower G_CTLZ in terms of it.
In order to achieve this we need to add support to the LegalizerHelper
for the legalization of G_CTLZ_ZERO_UNDEF for s32 as a libcall (__clzsi2).
We also need to allow lowering of G_CTLZ in terms of G_CTLZ_ZERO_UNDEF
if that is supported as a libcall, as opposed to just if it is Legal or
Custom. Due to a minor refactoring of the helper function in charge of
this, we will also allow the same behaviour for G_CTTZ and G_CTPOP.
This is not going to be a problem in practice since we don't yet have
support for treating G_CTTZ and G_CTPOP as libcalls (not even in
DAGISel).
Reg bank select:
Map G_CTLZ to GPR. G_CTLZ_ZERO_UNDEF should not make it to this point.
Instruction select:
Nothing to do.
llvm-svn: 347545
diff --git a/llvm/unittests/CodeGen/GlobalISel/LegalizerHelperTest.cpp b/llvm/unittests/CodeGen/GlobalISel/LegalizerHelperTest.cpp
index 0cc989b..f0527611 100644
--- a/llvm/unittests/CodeGen/GlobalISel/LegalizerHelperTest.cpp
+++ b/llvm/unittests/CodeGen/GlobalISel/LegalizerHelperTest.cpp
@@ -148,6 +148,33 @@
ASSERT_TRUE(CheckMachineFunction(*MF, CheckStr));
}
+// CTLZ expansion in terms of CTLZ_ZERO_UNDEF if the latter is a libcall
+TEST_F(LegalizerHelperTest, LowerBitCountingCTLZLibcall) {
+ if (!TM)
+ return;
+
+ // Declare your legalization info
+ DefineLegalizerInfo(
+ A, { getActionDefinitionsBuilder(G_CTLZ_ZERO_UNDEF).libcallFor({s64}); });
+ // Build
+ auto MIBCTLZ = B.buildInstr(TargetOpcode::G_CTLZ, LLT::scalar(64), Copies[0]);
+ AInfo Info(MF->getSubtarget());
+ LegalizerHelper Helper(*MF, Info);
+ ASSERT_TRUE(Helper.lower(*MIBCTLZ, 0, LLT::scalar(64)) ==
+ LegalizerHelper::LegalizeResult::Legalized);
+
+ auto CheckStr = R"(
+ CHECK: [[CZU:%[0-9]+]]:_(s64) = G_CTLZ_ZERO_UNDEF %0
+ CHECK: [[ZERO:%[0-9]+]]:_(s64) = G_CONSTANT i64 0
+ CHECK: [[THIRTY2:%[0-9]+]]:_(s64) = G_CONSTANT i64 64
+ CHECK: [[CMP:%[0-9]+]]:_(s1) = G_ICMP intpred(eq), %0:_(s64), [[ZERO]]
+ CHECK: [[SEL:%[0-9]+]]:_(s64) = G_SELECT [[CMP]]:_(s1), [[THIRTY2]]:_, [[CZU]]
+ )";
+
+ // Check
+ ASSERT_TRUE(CheckMachineFunction(*MF, CheckStr));
+}
+
// CTLZ expansion
TEST_F(LegalizerHelperTest, LowerBitCountingCTLZ1) {
if (!TM)