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llvm-mirror/test/TableGen/dag-isel-subregs.td
Stanislav Mekhanoshin 563a9ce27a [TBLGEN] Fix subreg value overflow in DAGISelMatcher
Tablegen's DAGISelMatcher emits integers in a VBR format,
so if an integer is below 128 it can fit into a single
byte, otherwise high bit is set, next byte is used etc.
MatcherTable is essentially an unsigned char table. When
SelectionDAGISel parses the table it does a reverse translation.

In a situation when numeric value of an integer to emit is
unknown it can be emitted not as OPC_EmitInteger but as
OPC_EmitStringInteger using a symbolic name of the value.
In this situation the value should not exceed 127.

One of the situations when OPC_EmitStringInteger is used is
if we need to emit a subreg into a matcher table. However,
number of subregs can exceed 127. Currently last defined subreg
for AMDGPU is 192. That results in a silent bug in the ISel
with matcher reading from an invalid offset.

Fixed this bug to emit actual VBR encoded value for a subregs
which value exceeds 127.

Differential Revision: https://reviews.llvm.org/D74368
2020-02-12 13:29:57 -08:00

15 lines
601 B
TableGen

// RUN: llvm-tblgen -gen-dag-isel -I %p/../../include -I %p/Common %s | FileCheck %s
include "reg-with-subregs-common.td"
// CHECK-LABEL: OPC_CheckOpcode, TARGET_VAL(ISD::EXTRACT_SUBVECTOR),
// CHECK: OPC_CheckChild1Integer, 0,
// CHECK: OPC_EmitInteger, MVT::i32, sub0_sub1,
def : Pat<(v2i32 (extract_subvector v32i32:$src, (i32 0))),
(EXTRACT_SUBREG GPR_1024:$src, sub0_sub1)>;
// CHECK: OPC_CheckChild1Integer, 15,
// CHECK: OPC_EmitInteger, MVT::i32, 5|128,1/*133*/,
def : Pat<(v2i32 (extract_subvector v32i32:$src, (i32 15))),
(EXTRACT_SUBREG GPR_1024:$src, sub30_sub31)>;