[AArch64/GCC] PR64304, miscompilation with -mgeneral-regs-only

[Jiong Wang]

as discussed here https://gcc.gnu.org/ml/gcc-patches/2015-01/msg00563.html

the problem is aarch64 hardware only support left shift truncation for SI/DI,
while SHIFT_COUNT_TRUNCATED is enabled for all mode including QI/HI, which is
inconsistent with hardware feature.

there are two patterns defined for ashift:QI/HI, one for shift amount in register,
one for shift amount as constant.

this patch only remove the pattern for shift amount in register which cause the trouble.

no regression on bare metal test.
bootstrap OK.

ok for trunk?


2015-01-15 Jiong. Wang (jiong.wang@arm.com)
gcc/
PR64304
   * config/aarch64/aarch64.md (define_insn "*ashl<mode>3_insn"): Deleted.
   (ashl<mode>3): Don't expand if operands[2] is not constant.

gcc/testsuite/
   * gcc.target/aarch64/pr64304.c: New testcase.
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