[PATCH] D110555: [SPARC] Zero-extend the operands when doing UMULO on 64-bit integers

[Koakuma via Phabricator via llvm-commits]

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On SPARC, S/UMULO operation on 64-bit integers works by extending the value to 128-bit, then doing a multiplication and checking the upper half of the result.
This makes UMULO works correctly by putting a zero in the upper half rather than doing a sign extension.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D110555

Files:
  llvm/lib/Target/Sparc/SparcISelLowering.cpp
  llvm/test/CodeGen/SPARC/mulo-64-lowering.ll


Index: llvm/test/CodeGen/SPARC/mulo-64-lowering.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/SPARC/mulo-64-lowering.ll
@@ -0,0 +1,36 @@
+; RUN: llc -march=sparcv9 < %s | FileCheck %s
+
+declare { i64, i1 } @llvm.smul.with.overflow.i64(i64, i64)
+declare { i64, i1 } @llvm.umul.with.overflow.i64(i64, i64)
+
+; CHECK-LABEL: s:
+; CHECK: save %sp, -176, %sp
+; CHECK: srax %i0, 63, %o0
+; CHECK: srax %i1, 63, %o2
+; CHECK: mov     %i0, %o1
+; CHECK: call __multi3
+; CHECK: mov     %i1, %o3
+; CHECK: ret
+; CHECK-NEXT: restore %g0, %o1, %o0
+
+define i64 @s(i64 %0, i64 %1) {
+  %3 = call { i64, i1 } @llvm.smul.with.overflow.i64(i64 %0, i64 %1)
+  %4 = extractvalue { i64, i1 } %3, 0
+  ret i64 %4
+}
+
+; CHECK-label: u:
+; CHECK: save %sp, -176, %sp
+; CHECK: mov     0, %o0
+; CHECK: mov     %i0, %o1
+; CHECK: mov     %o0, %o2
+; CHECK: call __multi3
+; CHECK: mov     %i1, %o3
+; CHECK: ret
+; CHECK-NEXT: restore %g0, %o1, %o0
+
+define i64 @u(i64 %0, i64 %1) local_unnamed_addr #0 {
+  %3 = call { i64, i1 } @llvm.umul.with.overflow.i64(i64 %0, i64 %1)
+  %4 = extractvalue { i64, i1 } %3, 0
+  ret i64 %4
+}
Index: llvm/lib/Target/Sparc/SparcISelLowering.cpp
===================================================================
--- llvm/lib/Target/Sparc/SparcISelLowering.cpp
+++ llvm/lib/Target/Sparc/SparcISelLowering.cpp
@@ -2954,8 +2954,15 @@
   SDValue ShiftAmt = DAG.getConstant(63, dl, VT);
 
   SDValue RHS = Op.getOperand(1);
-  SDValue HiLHS = DAG.getNode(ISD::SRA, dl, VT, LHS, ShiftAmt);
-  SDValue HiRHS = DAG.getNode(ISD::SRA, dl, MVT::i64, RHS, ShiftAmt);
+  SDValue HiLHS, HiRHS;
+  if(isSigned) {
+    HiLHS = DAG.getNode(ISD::SRA, dl, VT, LHS, ShiftAmt);
+    HiRHS = DAG.getNode(ISD::SRA, dl, MVT::i64, RHS, ShiftAmt);
+  } else {
+    HiLHS = DAG.getConstant(0, dl, VT);
+    HiRHS = DAG.getConstant(0, dl, MVT::i64);
+  }
+
   SDValue Args[] = { HiLHS, LHS, HiRHS, RHS };
 
   TargetLowering::MakeLibCallOptions CallOptions;


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