Hello! As pointed out by Eric, there is this little detail in the documentation w.r.t sign and zero-extending conversions:
"For all conversion operations, X must not be `VOIDmode' because the mode in which to do the conversion would not be known. The conversion must either be done at compile-time or X must be placed into a register. Taking this into account, the fix is straightforward. We have to prevent VOIDmode immediates from entering ZERO_EXTEND RTX. 2012-04-09 Uros Bizjak <ubiz...@gmail.com> PR target/52883 * config/i386/predicates.md (x86_64_zext_general_operand): Prevent VOIDmode immediate operands. * config/i386/constraints.md (Wz): New constraint. * config/i386/i386.md (*zero_extendsidi2_rex64): Use Wz instead of Z. testsuite/ChangeLog: 2012-04-09 Uros Bizjak <ubiz...@gmail.com> PR target/52883 * gcc.target/i386/pr52883.c: New testcase. Patch was tested on x86_64-pc-linux-gnu {,-m32} and committed to mainline SVN. Uros.
Index: config/i386/i386.md =================================================================== --- config/i386/i386.md (revision 186236) +++ config/i386/i386.md (working copy) @@ -3393,10 +3393,10 @@ (define_insn "*zero_extendsidi2_rex64" [(set (match_operand:DI 0 "nonimmediate_operand" - "=r ,o,?*Ym,?*y,?*Yi,!*x") + "=r ,o,?*Ym,?*y,?*Yi,!*x") (zero_extend:DI (match_operand:SI 1 "x86_64_zext_general_operand" - "rmZ,0,r ,m ,r ,m*x")))] + "rmWz,0,r ,m ,r ,m*x")))] "TARGET_64BIT" "@ mov{l}\t{%1, %k0|%k0, %1} Index: config/i386/constraints.md =================================================================== --- config/i386/constraints.md (revision 186236) +++ config/i386/constraints.md (working copy) @@ -18,7 +18,7 @@ ;; <http://www.gnu.org/licenses/>. ;;; Unused letters: -;;; B H T W +;;; B H T ;;; h k v ;; Integer register constraints. @@ -199,6 +199,16 @@ instructions)." (match_operand 0 "x86_64_immediate_operand")) +;; We use W prefix to denote any number of +;; constant-or-symbol-reference constraints + +(define_constraint "Wz" + "32-bit unsigned integer constant, or a symbolic reference known + to fit that range (for zero-extending conversion operations that + require non-VOIDmode immediate operands)." + (and (match_operand 0 "x86_64_zext_immediate_operand") + (match_test "GET_MODE (op) != VOIDmode"))) + (define_constraint "Z" "32-bit unsigned integer constant, or a symbolic reference known to fit that range (for immediate operands in zero-extending x86-64 Index: config/i386/predicates.md =================================================================== --- config/i386/predicates.md (revision 186236) +++ config/i386/predicates.md (working copy) @@ -341,11 +341,13 @@ (match_operand 0 "general_operand"))) ;; Return true if OP is general operand representable on x86_64 -;; as zero extended constant. +;; as zero extended constant. This predicate is used in zero-extending +;; conversion operations that require non-VOIDmode immediate operands. (define_predicate "x86_64_zext_general_operand" (if_then_else (match_test "TARGET_64BIT") (ior (match_operand 0 "nonimmediate_operand") - (match_operand 0 "x86_64_zext_immediate_operand")) + (and (match_operand 0 "x86_64_zext_immediate_operand") + (match_test "GET_MODE (op) != VOIDmode"))) (match_operand 0 "general_operand"))) ;; Return true if OP is general operand representable on x86_64 Index: testsuite/gcc.target/i386/pr52883.c =================================================================== --- testsuite/gcc.target/i386/pr52883.c (revision 0) +++ testsuite/gcc.target/i386/pr52883.c (revision 0) @@ -0,0 +1,25 @@ +/* { dg-do compile } */ +/* { dg-options "-O" } */ + +int a, b, d, e, f, i, j, k, l, m; +unsigned c; +int g[] = { }, h[0]; + +int +fn1 () { + return 0; +} + +void +fn2 () { + c = 0; + e = 0; + for (;; e = 0) + if (f > j) { + k = fn1 (); + l = (d || k) * b; + m = l * a; + h[0] = m <= i; + } else + i = g[c]; +}