[PATCH] D107082: [X86][RFC] Enable `_Float16` type support on X86 following the psABI

[LuoYuanke via Phabricator via llvm-commits]

LuoYuanke added inline comments.


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Comment at: llvm/test/CodeGen/X86/fpclamptosat.ll:569
 ; CHECK-NEXT:    cvttss2si %xmm0, %rax
 ; CHECK-NEXT:    ucomiss {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
+; CHECK-NEXT:    movabsq $-9223372036854775808, %rcx # imm = 0x8000000000000000
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I'm curious why there is 1 more compare in this patch. 


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Comment at: llvm/test/CodeGen/X86/fpclamptosat.ll:776
+; CHECK-NEXT:    cmovael %eax, %ecx
+; CHECK-NEXT:    ucomiss {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
+; CHECK-NEXT:    movl $2147483647, %edx # imm = 0x7FFFFFFF
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Ditto.


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Comment at: llvm/test/CodeGen/X86/fpclamptosat_vec.ll:605
+; CHECK-NEXT:    .cfi_def_cfa_offset 80
+; CHECK-NEXT:    movss %xmm2, {{[-0-9]+}}(%r{{[sb]}}p) # 4-byte Spill
+; CHECK-NEXT:    movss %xmm1, {{[-0-9]+}}(%r{{[sb]}}p) # 4-byte Spill
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Is the vector <4 x half> split to 4 scalar and pass by xmm? What's the ABI for vector half? Is there any case that test the scenario that run out of register and pass parameter through stack?


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Comment at: llvm/test/CodeGen/X86/fptosi-sat-scalar.ll:2138
+; X64-NEXT:    ucomiss {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
+; X64-NEXT:    movl $255, %eax
+; X64-NEXT:    cmovael %ecx, %eax
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It seems less efficient than previous code on NAN, zero handling, but we can improve later.


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Comment at: llvm/test/CodeGen/X86/half.ll:946
+; CHECK-I686-NEXT:    calll __extendhfsf2
+; CHECK-I686-NEXT:    fstps {{[0-9]+}}(%esp)
+; CHECK-I686-NEXT:    movss {{.*#+}} xmm0 = mem[0],zero,zero,zero
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Why the x87 instruction is generated?


Repository:
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https://reviews.llvm.org/D107082