[NVPTX] expand mul_lohi to mul_lo and mul_hi

Summary: Fixes PR26186. Reviewers: grosser, jholewinski Subscribers: jholewinski, llvm-commits Differential Revision: http://reviews.llvm.org/D16479 llvm-svn: 258536
llvm · Jan 22, 2016 · 585ec86 · 585ec86
1 parent d5607d3
commit 585ec86
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diff --git a/llvm/lib/Target/NVPTX/NVPTXISelLowering.cpp b/llvm/lib/Target/NVPTX/NVPTXISelLowering.cpp
@@ -273,6 +273,10 @@ NVPTXTargetLowering::NVPTXTargetLowering(const NVPTXTargetMachine &TM,
   // PTX does not directly support SELP of i1, so promote to i32 first
   setOperationAction(ISD::SELECT, MVT::i1, Custom);
 
+  // PTX cannot multiply two i64s in a single instruction.
+  setOperationAction(ISD::SMUL_LOHI, MVT::i64, Expand);
+  setOperationAction(ISD::UMUL_LOHI, MVT::i64, Expand);
+
   // We have some custom DAG combine patterns for these nodes
   setTargetDAGCombine(ISD::ADD);
   setTargetDAGCombine(ISD::AND);

diff --git a/llvm/test/CodeGen/NVPTX/arithmetic-int.ll b/llvm/test/CodeGen/NVPTX/arithmetic-int.ll
@@ -29,6 +29,30 @@ define i64 @mul_i64(i64 %a, i64 %b) {
   ret i64 %ret
 }
 
+define i64 @umul_lohi_i64(i64 %a) {
+; CHECK-LABEL: umul_lohi_i64(
+entry:
+  %0 = zext i64 %a to i128
+  %1 = mul i128 %0, 288
+; CHECK: mul.lo.{{u|s}}64
+; CHECK: mul.hi.{{u|s}}64
+  %2 = lshr i128 %1, 1
+  %3 = trunc i128 %2 to i64
+  ret i64 %3
+}
+
+define i64 @smul_lohi_i64(i64 %a) {
+; CHECK-LABEL: smul_lohi_i64(
+entry:
+  %0 = sext i64 %a to i128
+  %1 = mul i128 %0, 288
+; CHECK: mul.lo.{{u|s}}64
+; CHECK: mul.hi.{{u|s}}64
+  %2 = ashr i128 %1, 1
+  %3 = trunc i128 %2 to i64
+  ret i64 %3
+}
+
 define i64 @sdiv_i64(i64 %a, i64 %b) {
 ; CHECK: div.s64 %rd{{[0-9]+}}, %rd{{[0-9]+}}, %rd{{[0-9]+}}
 ; CHECK: ret