Wrong FNSTSW size operator.

[m_zuckerman]

Summary

By intel spec

9B DD /7	FSTSW m2byte	Valid Valid Store FPU status word at m2byteafter checking for pending unmasked floating-point exceptions.
9B DF E0	FSTSW AX	Valid Valid Store FPU status word in AX register after checking for pending unmasked floating-point exceptions.
DD /7	FNSTSW *m2byte	Valid Valid Store FPU status word at m2bytewithout checking for pending unmasked floating-point exceptions.
DF E0	FNSTSW *AX	Valid Valid Store FPU status word in AX register without checking for pending unmasked floating-point exceptions

m2byte is word register, and therefor instruction operand need to be change from f32mem to i16mem.

[m_zuckerman]

PING

[craig.topper]

LGTM

[mcrosier]

Is there no way to test this?

llvm/trunk/lib/Target/X86/X86InstrFPStack.td

 def FICOM32m : FPI<0xDA, MRM2m, (outs), (ins i32mem:$src), "ficom{l}\t$src">;
 def FICOMP32m: FPI<0xDA, MRM3m, (outs), (ins i32mem:$src), "ficomp{l}\t$src">;
 
 def FCOM64m  : FPI<0xDC, MRM2m, (outs), (ins f64mem:$src), "fcom{l}\t$src">;
 def FCOMP64m : FPI<0xDC, MRM3m, (outs), (ins f64mem:$src), "fcomp{l}\t$src">;
 
 def FRSTORm  : FPI<0xDD, MRM4m, (outs f32mem:$dst), (ins), "frstor\t$dst">;
 def FSAVEm   : FPI<0xDD, MRM6m, (outs f32mem:$dst), (ins), "fnsave\t$dst">;
-def FNSTSWm  : FPI<0xDD, MRM7m, (outs f32mem:$dst), (ins), "fnstsw\t$dst">;
+def FNSTSWm  : FPI<0xDD, MRM7m, (outs i16mem:$dst), (ins), "fnstsw\t$dst">;
 
 def FICOM16m : FPI<0xDE, MRM2m, (outs), (ins i16mem:$src), "ficom{s}\t$src">;
 def FICOMP16m: FPI<0xDE, MRM3m, (outs), (ins i16mem:$src), "ficomp{s}\t$src">;
 
 def FBLDm    : FPI<0xDF, MRM4m, (outs), (ins f80mem:$src), "fbld\t$src">;
 def FBSTPm   : FPI<0xDF, MRM6m, (outs f80mem:$dst), (ins), "fbstp\t$dst">;
 
 // Floating point cmovs.