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Removed unnecessary Zero checking on FmaPreResultSubnorm

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This commit is contained in:
David Harris 2024-06-10 07:45:03 -07:00
parent 4c066c078f
commit 3284dd2112
1 changed files with 10 additions and 10 deletions
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20
src/fpu/postproc/fmashiftcalc.sv
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@ -78,19 +78,19 @@ module fmashiftcalc import cvw::*; #(parameter cvw_t P) (
assign NormSumExp = PreNormSumExp+BiasCorr;
end
// determine if the result is subnormal: (NormSumExp <= 0) & (NormSumExp >= -FracLen) & ~FmaSZero
// determine if the result is subnormal: (NormSumExp <= 0) & (NormSumExp >= -FracLen)
if (P.FPSIZES == 1) begin
logic Sum0LEZ, Sum0GEFL;
assign Sum0LEZ = PreNormSumExp[P.NE+1] | ~|PreNormSumExp;
assign Sum0GEFL = $signed(PreNormSumExp) >= $signed((P.NE+2)'(-P.NF-1)); // changed from -2 dh 4/3/24 for issue 655
assign FmaPreResultSubnorm = Sum0LEZ & Sum0GEFL & ~FmaSZero;
assign FmaPreResultSubnorm = Sum0LEZ & Sum0GEFL;
end else if (P.FPSIZES == 2) begin
logic Sum0LEZ, Sum0GEFL, Sum1LEZ, Sum1GEFL;
assign Sum0LEZ = PreNormSumExp[P.NE+1] | ~|PreNormSumExp;
assign Sum0GEFL = $signed(PreNormSumExp) >= $signed((P.NE+2)'(-P.NF-1)); // changed from -2 dh 4/3/24 for issue 655
assign Sum1LEZ = $signed(PreNormSumExp) <= $signed((P.NE+2)'(P.BIAS-P.BIAS1));
assign Sum1GEFL = $signed(PreNormSumExp) >= $signed((P.NE+2)'(-P.NF1-1+P.BIAS-P.BIAS1)) | ~|PreNormSumExp;
assign FmaPreResultSubnorm = (Fmt ? Sum0LEZ : Sum1LEZ) & (Fmt ? Sum0GEFL : Sum1GEFL) & ~FmaSZero;
assign FmaPreResultSubnorm = (Fmt ? Sum0LEZ : Sum1LEZ) & (Fmt ? Sum0GEFL : Sum1GEFL);
end else if (P.FPSIZES == 3) begin
logic Sum0LEZ, Sum0GEFL, Sum1LEZ, Sum1GEFL, Sum2LEZ, Sum2GEFL;
assign Sum0LEZ = PreNormSumExp[P.NE+1] | ~|PreNormSumExp;
@ -101,9 +101,9 @@ module fmashiftcalc import cvw::*; #(parameter cvw_t P) (
assign Sum2GEFL = $signed(PreNormSumExp) >= $signed((P.NE+2)'(-P.NF2-1+P.BIAS-P.BIAS2)) | ~|PreNormSumExp;
always_comb begin
case (Fmt)
P.FMT: FmaPreResultSubnorm = Sum0LEZ & Sum0GEFL; // & ~FmaSZero; // checking sum is not zero is harmless but turns out to be unnecessary
P.FMT1: FmaPreResultSubnorm = Sum1LEZ & Sum1GEFL; // & ~FmaSZero;
P.FMT2: FmaPreResultSubnorm = Sum2LEZ & Sum2GEFL; // & ~FmaSZero;
P.FMT: FmaPreResultSubnorm = Sum0LEZ & Sum0GEFL;
P.FMT1: FmaPreResultSubnorm = Sum1LEZ & Sum1GEFL;
P.FMT2: FmaPreResultSubnorm = Sum2LEZ & Sum2GEFL;
default: FmaPreResultSubnorm = 1'bx;
endcase
end
@ -119,10 +119,10 @@ module fmashiftcalc import cvw::*; #(parameter cvw_t P) (
assign Sum3GEFL = $signed(PreNormSumExp) >= $signed((P.NE+2)'(-P.H_NF-1+P.BIAS-P.H_BIAS)) | ~|PreNormSumExp;
always_comb begin
case (Fmt)
2'h3: FmaPreResultSubnorm = Sum0LEZ & Sum0GEFL & ~FmaSZero;
2'h1: FmaPreResultSubnorm = Sum1LEZ & Sum1GEFL & ~FmaSZero;
2'h0: FmaPreResultSubnorm = Sum2LEZ & Sum2GEFL & ~FmaSZero;
2'h2: FmaPreResultSubnorm = Sum3LEZ & Sum3GEFL & ~FmaSZero;
2'h3: FmaPreResultSubnorm = Sum0LEZ & Sum0GEFL;
2'h1: FmaPreResultSubnorm = Sum1LEZ & Sum1GEFL;
2'h0: FmaPreResultSubnorm = Sum2LEZ & Sum2GEFL;
2'h2: FmaPreResultSubnorm = Sum3LEZ & Sum3GEFL;
endcase
end
end