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Improve codegen for the various "with overflow" intrinsics
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We're currently possibly introducing an unneeded temporary, make use of
InsertValue which is said to kick us off of FastISel and we generate
loads/stores of first class aggregates, which is bad as well. Let's not
do all these things.
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@dotdash
dotdash committed Aug 23, 2015
1 parent 2375743 commit 274dae9
Showing 1 changed file with 29 additions and 35 deletions.
64 changes: 29 additions & 35 deletions src/librustc_trans/trans/intrinsic.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -616,171 +616,171 @@ pub fn trans_intrinsic_call<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
(_, "i8_add_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.sadd.with.overflow.i8",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "i16_add_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.sadd.with.overflow.i16",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "i32_add_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.sadd.with.overflow.i32",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "i64_add_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.sadd.with.overflow.i64",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),

(_, "u8_add_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.uadd.with.overflow.i8",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "u16_add_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.uadd.with.overflow.i16",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "u32_add_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.uadd.with.overflow.i32",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "u64_add_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.uadd.with.overflow.i64",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "i8_sub_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.ssub.with.overflow.i8",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "i16_sub_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.ssub.with.overflow.i16",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "i32_sub_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.ssub.with.overflow.i32",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "i64_sub_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.ssub.with.overflow.i64",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "u8_sub_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.usub.with.overflow.i8",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "u16_sub_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.usub.with.overflow.i16",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "u32_sub_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.usub.with.overflow.i32",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "u64_sub_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.usub.with.overflow.i64",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "i8_mul_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.smul.with.overflow.i8",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "i16_mul_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.smul.with.overflow.i16",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "i32_mul_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.smul.with.overflow.i32",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "i64_mul_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.smul.with.overflow.i64",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "u8_mul_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.umul.with.overflow.i8",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "u16_mul_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.umul.with.overflow.i16",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "u32_mul_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.umul.with.overflow.i32",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),
(_, "u64_mul_with_overflow") =>
with_overflow_intrinsic(bcx,
"llvm.umul.with.overflow.i64",
ret_ty,
llargs[0],
llargs[1],
llresult,
call_debug_location),

(_, "unchecked_udiv") => UDiv(bcx, llargs[0], llargs[1], call_debug_location),
Expand Down Expand Up @@ -1053,9 +1053,9 @@ fn count_zeros_intrinsic(bcx: Block,

fn with_overflow_intrinsic<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
name: &'static str,
t: Ty<'tcx>,
a: ValueRef,
b: ValueRef,
out: ValueRef,
call_debug_location: DebugLoc)
-> ValueRef {
let llfn = bcx.ccx().get_intrinsic(&name);
Expand All @@ -1064,16 +1064,10 @@ fn with_overflow_intrinsic<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
let val = Call(bcx, llfn, &[a, b], None, call_debug_location);
let result = ExtractValue(bcx, val, 0);
let overflow = ZExt(bcx, ExtractValue(bcx, val, 1), Type::bool(bcx.ccx()));
let ret = C_undef(type_of::type_of(bcx.ccx(), t));
let ret = InsertValue(bcx, ret, result, 0);
let ret = InsertValue(bcx, ret, overflow, 1);
if !arg_is_indirect(bcx.ccx(), t) {
let tmp = alloc_ty(bcx, t, "tmp");
Store(bcx, ret, tmp);
load_ty(bcx, tmp, t)
} else {
ret
}
Store(bcx, result, StructGEP(bcx, out, 0));
Store(bcx, overflow, StructGEP(bcx, out, 1));

C_nil(bcx.ccx())
}

fn try_intrinsic<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
Expand Down

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