diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Solver/STPBuilder.cpp | 92 | ||||
| -rw-r--r-- | lib/Solver/STPBuilder.h | 2 |
2 files changed, 57 insertions, 37 deletions
diff --git a/lib/Solver/STPBuilder.cpp b/lib/Solver/STPBuilder.cpp index 307ae0fb..8ec35762 100644 --- a/lib/Solver/STPBuilder.cpp +++ b/lib/Solver/STPBuilder.cpp @@ -152,6 +152,7 @@ ExprHandle STPBuilder::bvExtract(ExprHandle expr, unsigned top, unsigned bottom) return vc_bvExtract(vc, expr, top, bottom); } ExprHandle STPBuilder::eqExpr(ExprHandle a, ExprHandle b) { + assert((vc_getBVLength(vc, a) == vc_getBVLength(vc, b)) && "a and b should be same type"); return vc_eqExpr(vc, a, b); } @@ -187,76 +188,93 @@ ExprHandle STPBuilder::bvLeftShift(ExprHandle expr, unsigned shift) { } } +ExprHandle STPBuilder::extractPartialShiftValue(ExprHandle shift, + unsigned width, + unsigned &shiftBits) { + // Assuming width is power of 2 + llvm::APInt sw(32, width); + shiftBits = sw.getActiveBits(); + + // get the shift amount (looking only at the bits appropriate for the given + // width) + return vc_bvExtract(vc, shift, shiftBits - 1, 0); +} + // left shift by a variable amount on an expression of the specified width ExprHandle STPBuilder::bvVarLeftShift(ExprHandle expr, ExprHandle shift) { unsigned width = vc_getBVLength(vc, expr); ExprHandle res = bvZero(width); - //construct a big if-then-elif-elif-... with one case per possible shift amount - for( int i=width-1; i>=0; i-- ) { - res = vc_iteExpr(vc, - eqExpr(shift, bvConst32(width, i)), - bvLeftShift(expr, i), - res); + unsigned shiftBits = 0; + ExprHandle shift_ext = extractPartialShiftValue(shift, width, shiftBits); + + // construct a big if-then-elif-elif-... with one case per possible shift + // amount + for (int i = width - 1; i >= 0; i--) { + res = vc_iteExpr(vc, eqExpr(shift_ext, bvConst32(shiftBits, i)), + bvLeftShift(expr, i), res); } // If overshifting, shift to zero - ExprHandle ex = vc_bvLtExpr(vc, shift, bvConst32(vc_getBVLength(vc,shift), width)); + ExprHandle ex = + vc_bvLtExpr(vc, shift, bvConst32(vc_getBVLength(vc, shift), width)); res = vc_iteExpr(vc, ex, res, bvZero(width)); return res; } -// logical right shift by a variable amount on an expression of the specified width +// logical right shift by a variable amount on an expression of the specified +// width ExprHandle STPBuilder::bvVarRightShift(ExprHandle expr, ExprHandle shift) { unsigned width = vc_getBVLength(vc, expr); ExprHandle res = bvZero(width); - //construct a big if-then-elif-elif-... with one case per possible shift amount - for( int i=width-1; i>=0; i-- ) { - res = vc_iteExpr(vc, - eqExpr(shift, bvConst32(width, i)), - bvRightShift(expr, i), - res); + unsigned shiftBits = 0; + ExprHandle shift_ext = extractPartialShiftValue(shift, width, shiftBits); + + // construct a big if-then-elif-elif-... with one case per possible shift + // amount + for (int i = width - 1; i >= 0; i--) { + res = vc_iteExpr(vc, eqExpr(shift_ext, bvConst32(shiftBits, i)), + bvRightShift(expr, i), res); } // If overshifting, shift to zero - ExprHandle ex = vc_bvLtExpr(vc, shift, bvConst32(vc_getBVLength(vc,shift), width)); - res = vc_iteExpr(vc, - ex, - res, - bvZero(width)); + // If overshifting, shift to zero + ExprHandle ex = + vc_bvLtExpr(vc, shift, bvConst32(vc_getBVLength(vc, shift), width)); + res = vc_iteExpr(vc, ex, res, bvZero(width)); + return res; } -// arithmetic right shift by a variable amount on an expression of the specified width +// arithmetic right shift by a variable amount on an expression of the specified +// width ExprHandle STPBuilder::bvVarArithRightShift(ExprHandle expr, ExprHandle shift) { unsigned width = vc_getBVLength(vc, expr); - //get the sign bit to fill with - ExprHandle signedBool = bvBoolExtract(expr, width-1); + unsigned shiftBits = 0; + ExprHandle shift_ext = extractPartialShiftValue(shift, width, shiftBits); - //start with the result if shifting by width-1 - ExprHandle res = constructAShrByConstant(expr, width-1, signedBool); + // get the sign bit to fill with + ExprHandle signedBool = bvBoolExtract(expr, width - 1); - //construct a big if-then-elif-elif-... with one case per possible shift amount + // start with the result if shifting by width-1 + ExprHandle res = constructAShrByConstant(expr, width - 1, signedBool); + + // construct a big if-then-elif-elif-... with one case per possible shift + // amount // XXX more efficient to move the ite on the sign outside all exprs? // XXX more efficient to sign extend, right shift, then extract lower bits? - for( int i=width-2; i>=0; i-- ) { - res = vc_iteExpr(vc, - eqExpr(shift, bvConst32(width,i)), - constructAShrByConstant(expr, - i, - signedBool), - res); + for (int i = width - 2; i >= 0; i--) { + res = vc_iteExpr(vc, eqExpr(shift_ext, bvConst32(shiftBits, i)), + constructAShrByConstant(expr, i, signedBool), res); } // If overshifting, shift to zero - ExprHandle ex = vc_bvLtExpr(vc, shift, bvConst32(vc_getBVLength(vc,shift), width)); - res = vc_iteExpr(vc, - ex, - res, - bvZero(width)); + ExprHandle ex = + vc_bvLtExpr(vc, shift, bvConst32(vc_getBVLength(vc, shift), width)); + res = vc_iteExpr(vc, ex, res, bvZero(width)); return res; } diff --git a/lib/Solver/STPBuilder.h b/lib/Solver/STPBuilder.h index 3b17ccf1..5be34029 100644 --- a/lib/Solver/STPBuilder.h +++ b/lib/Solver/STPBuilder.h @@ -93,6 +93,8 @@ private: ExprHandle bvVarLeftShift(ExprHandle expr, ExprHandle shift); ExprHandle bvVarRightShift(ExprHandle expr, ExprHandle shift); ExprHandle bvVarArithRightShift(ExprHandle expr, ExprHandle shift); + ExprHandle extractPartialShiftValue(ExprHandle shift, unsigned width, + unsigned &shiftBits); ExprHandle constructAShrByConstant(ExprHandle expr, unsigned shift, ExprHandle isSigned); |