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llvm-mirror/test/Transforms/SCCP/ub-shift.ll
David Majnemer 7230d61b65 [SCCP] Resolve shifts beyond the bitwidth to undef
Shifts beyond the bitwidth are undef but SCCP resolved them to zero.
Instead, DTRT and resolve them to undef.

This reimplements the transform which caused PR27712.

llvm-svn: 269269
2016-05-12 03:07:40 +00:00

70 lines
1.5 KiB
LLVM

; RUN: opt < %s -sccp -S | FileCheck %s
; CHECK-LABEL: shift_undef_64
define void @shift_undef_64(i64* %p) {
%r1 = lshr i64 -1, 4294967296 ; 2^32
; CHECK: store i64 undef
store i64 %r1, i64* %p
%r2 = ashr i64 -1, 4294967297 ; 2^32 + 1
; CHECK: store i64 undef
store i64 %r2, i64* %p
%r3 = shl i64 -1, 4294967298 ; 2^32 + 2
; CHECK: store i64 undef
store i64 %r3, i64* %p
ret void
}
; CHECK-LABEL: shift_undef_65
define void @shift_undef_65(i65* %p) {
%r1 = lshr i65 2, 18446744073709551617
; CHECK: store i65 undef
store i65 %r1, i65* %p
%r2 = ashr i65 4, 18446744073709551617
; CHECK: store i65 undef
store i65 %r2, i65* %p
%r3 = shl i65 1, 18446744073709551617
; CHECK: store i65 undef
store i65 %r3, i65* %p
ret void
}
; CHECK-LABEL: shift_undef_256
define void @shift_undef_256(i256* %p) {
%r1 = lshr i256 2, 18446744073709551617
; CHECK: store i256 undef
store i256 %r1, i256* %p
%r2 = ashr i256 4, 18446744073709551618
; CHECK: store i256 undef
store i256 %r2, i256* %p
%r3 = shl i256 1, 18446744073709551619
; CHECK: store i256 undef
store i256 %r3, i256* %p
ret void
}
; CHECK-LABEL: shift_undef_511
define void @shift_undef_511(i511* %p) {
%r1 = lshr i511 -1, 1208925819614629174706276 ; 2^80 + 100
; CHECK: store i511 undef
store i511 %r1, i511* %p
%r2 = ashr i511 -2, 1208925819614629174706200
; CHECK: store i511 undef
store i511 %r2, i511* %p
%r3 = shl i511 -3, 1208925819614629174706180
; CHECK: store i511 undef
store i511 %r3, i511* %p
ret void
}