Fix vector packing pseudo-instruction.

When the first source register is different from the destination register, but equal to the second source, we need to first narrow the second source to prevent overwriting data we still need. Similar when the destination is equal to the first source. Bug b/37496082 Change-Id: I908a8e125a77ec4bf1eb5eab9e48c6112ee4ca13 Reviewed-on: https://chromium-review.googlesource.com/696032Reviewed-by: Jim Stichnoth <stichnot@chromium.org> Reviewed-on: https://swiftshader-review.googlesource.com/12949Reviewed-by: Nicolas Capens <nicolascapens@google.com> Tested-by: Nicolas Capens <nicolascapens@google.com>

Fix vector packing pseudo-instruction.
416cfb9f · Nicolas Capens · Nicolas Capens · 355a5dc1 · 416cfb9f
Commit 416cfb9f authored Oct 02, 2017 by Nicolas Capens Committed by Nicolas Capens Oct 03, 2017
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IceAssemblerARM32.cpp third_party/subzero/src/IceAssemblerARM32.cpp +4 -5

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--- a/third_party/subzero/src/IceAssemblerARM32.cpp
+++ b/third_party/subzero/src/IceAssemblerARM32.cpp
@@ -3731,16 +3731,15 @@ void AssemblerARM32::vqmovn2(Type DestElmtTy, const Operand *OpQd,
  VqmovnOpcode |= (encodeElmtType(DestElmtTy) << ElmtShift);
  if (Qm != Qd) {
-    // Narrow first source operand to lower half of destination.
-    emitSIMDBase(VqmovnOpcode, Dd + 0, 0, Dm, UseQRegs, IsFloatTy);
    // Narrow second source operand to upper half of destination.
    emitSIMDBase(VqmovnOpcode, Dd + 1, 0, Dn, UseQRegs, IsFloatTy);
+    // Narrow first source operand to lower half of destination.
+    emitSIMDBase(VqmovnOpcode, Dd + 0, 0, Dm, UseQRegs, IsFloatTy);
  } else if (Qn != Qd) {
-    // Narrow second source operand to upper half of destination.
-    emitSIMDBase(VqmovnOpcode, Dd + 1, 0, Dn, UseQRegs, IsFloatTy);
    // Narrow first source operand to lower half of destination.
    emitSIMDBase(VqmovnOpcode, Dd + 0, 0, Dm, UseQRegs, IsFloatTy);
+    // Narrow second source operand to upper half of destination.
+    emitSIMDBase(VqmovnOpcode, Dd + 1, 0, Dn, UseQRegs, IsFloatTy);
  } else {
    // Narrow first source operand to lower half of destination.
    emitSIMDBase(VqmovnOpcode, Dd, 0, Dm, UseQRegs, IsFloatTy);