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Fix regression due to early constant folding in +: and -: (#2338)

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Geza Lore 2020-05-18 18:46:00 +01:00 committed by GitHub
parent 0f7677480f
commit d20a4db773
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2 changed files with 16 additions and 0 deletions
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1
src/V3WidthSel.cpp
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@ -458,6 +458,7 @@ private:
UINFO(6, "SELPLUS/MINUS " << nodep << endl);
// Below 2 lines may change nodep->widthp()
if (debug() >= 9) nodep->dumpTree(cout, "--SELPM0: ");
V3Width::widthParamsEdit(nodep->rhsp()); // constifyEdit doesn't ensure widths finished
V3Const::constifyEdit(nodep->rhsp()); // May relink pointed to node, ok if not const
V3Const::constifyParamsEdit(nodep->thsp()); // May relink pointed to node
checkConstantOrReplace(nodep->thsp(), "Width of :+ or :- bit extract isn't a constant");

15
test_regress/t/t_select_plus.v
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@ -74,4 +74,19 @@ module t (/*AUTOARG*/
endcase
end
// Additional constant folding check - this used to trigger a bug
reg [23:0] a;
reg [3:0] b;
initial begin
a = 24'd0;
b = 4'b0111;
a[3*(b[2:0]+0)+:3] = 3'd7; // Check LSB expression goes to 32-bits
if (a != 24'b11100000_00000000_00000000) $stop;
a = 24'd0;
b = 4'b0110;
a[3*(b[2:0]+0)-:3] = 3'd7; // Check MSB expression goes to 32-bits
if (a != 24'b00000111_00000000_00000000) $stop;
end
endmodule