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AMDGPU/SI: Improve register allocation hints for sopk instructions

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Summary:
For shrinking SOPK instructions, we were creating a hint to tell the
register allocator to use the register allocated for src0 for the dst
operand as well.  However, this seems to not work sometimes depending
on the order virtual registers are assigned physical registers.

To fix this, I've added a second allocation hint which does the reverse,
asks that the register allocated for dst is used for src0.

Reviewers: arsenm

Subscribers: arsenm, llvm-commits, kzhuravl

Differential Revision: https://reviews.llvm.org/D23862

llvm-svn: 279968
This commit is contained in:
Tom Stellard 2016-08-29 13:06:10 +00:00
parent 2aeb8bcd81
commit 12f6142ff9
2 changed files with 3 additions and 2 deletions
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1
lib/Target/AMDGPU/SIShrinkInstructions.cpp
View File

@ -282,6 +282,7 @@ bool SIShrinkInstructions::runOnMachineFunction(MachineFunction &MF) {
if (TargetRegisterInfo::isVirtualRegister(Dest.getReg()) &&
Src0.isReg()) {
MRI.setRegAllocationHint(Dest.getReg(), 0, Src0.getReg());
MRI.setRegAllocationHint(Src0.getReg(), 0, Dest.getReg());
continue;
}

4
test/CodeGen/AMDGPU/shl_add_constant.ll
View File

@ -74,8 +74,8 @@ define void @test_add_shl_add_constant(i32 addrspace(1)* %out, i32 %x, i32 %y) #
; SI-DAG: s_load_dword [[Y:s[0-9]+]], s{{\[[0-9]+:[0-9]+\]}}, 0xc
; SI: s_lshl_b32 [[SHL3:s[0-9]+]], [[X]], 3
; SI: s_add_i32 [[TMP:s[0-9]+]], [[Y]], [[SHL3]]
; SI: s_add_i32 [[RESULT:s[0-9]+]], [[TMP]], 0x3d8
; SI: v_mov_b32_e32 [[VRESULT:v[0-9]+]], [[RESULT]]
; SI: s_addk_i32 [[TMP]], 0x3d8
; SI: v_mov_b32_e32 [[VRESULT:v[0-9]+]], [[TMP]]
; SI: buffer_store_dword [[VRESULT]]
define void @test_add_shl_add_constant_inv(i32 addrspace(1)* %out, i32 %x, i32 %y) #0 {