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SelectionDAG: Select min/max when both are used 

Allow two users of the condition if the other user
is also a min/max select. i.e.

%c = icmp slt i32 %x, %y
%min = select i1 %c, i32 %x, i32 %y
%max = select i1 %c, i32 %y, i32 %x

llvm-svn: 269699
This commit is contained in:
Matt Arsenault 2016-05-16 20:58:23 +00:00
parent da255efa2a
commit c31a9d0671
3 changed files with 95 additions and 2 deletions
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10
llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
View File

@ -2697,6 +2697,14 @@ void SelectionDAGBuilder::visitFCmp(const User &I) {
setValue(&I, DAG.getSetCC(getCurSDLoc(), DestVT, Op1, Op2, Condition));
}
// Check if the condition of the select has one use or two users that are both
// selects with the same condition.
bool hasOnlySelectUsers(const Value *Cond) {
return std::all_of(Cond->user_begin(), Cond->user_end(), [](const Value *V) {
return isa<SelectInst>(V);
});
}
void SelectionDAGBuilder::visitSelect(const User &I) {
SmallVector<EVT, 4> ValueVTs;
ComputeValueVTs(DAG.getTargetLoweringInfo(), DAG.getDataLayout(), I.getType(),
@ -2782,7 +2790,7 @@ void SelectionDAGBuilder::visitSelect(const User &I) {
// If the underlying comparison instruction is used by any other
// instruction, the consumed instructions won't be destroyed, so it is
// not profitable to convert to a min/max.
cast<SelectInst>(&I)->getCondition()->hasOneUse()) {
hasOnlySelectUsers(cast<SelectInst>(I).getCondition())) {
OpCode = Opc;
LHSVal = getValue(LHS);
RHSVal = getValue(RHS);

14
llvm/test/CodeGen/AMDGPU/select-i1.ll
View File

@ -1,4 +1,4 @@
; RUN: llc -march=amdgcn -mcpu=SI -verify-machineinstrs < %s | FileCheck -check-prefix=SI -check-prefix=FUNC %s
; RUN: llc -march=amdgcn -verify-machineinstrs < %s | FileCheck -check-prefix=SI -check-prefix=FUNC %s
; RUN: llc -march=amdgcn -mcpu=tonga -verify-machineinstrs < %s | FileCheck -check-prefix=SI -check-prefix=FUNC %s
; FIXME: This should go in existing select.ll test, except the current testcase there is broken on SI
@ -13,3 +13,15 @@ define void @select_i1(i1 addrspace(1)* %out, i32 %cond, i1 %a, i1 %b) nounwind
ret void
}
; FUNC-LABEL: {{^}}s_minmax_i1:
; SI-DAG: buffer_load_ubyte [[COND:v[0-9]+]], off, s{{\[[0-9]+:[0-9]+\]}}, 0 offset:44
; SI-DAG: buffer_load_ubyte [[A:v[0-9]+]], off, s{{\[[0-9]+:[0-9]+\]}}, 0 offset:45
; SI-DAG: buffer_load_ubyte [[B:v[0-9]+]], off, s{{\[[0-9]+:[0-9]+\]}}, 0 offset:46
; SI: v_cmp_eq_i32_e32 vcc, 1, [[COND]]
; SI: v_cndmask_b32_e32 v{{[0-9]+}}, [[B]], [[A]]
define void @s_minmax_i1(i1 addrspace(1)* %out, i1 zeroext %cond, i1 zeroext %a, i1 zeroext %b) nounwind {
%cmp = icmp slt i1 %cond, false
%sel = select i1 %cmp, i1 %a, i1 %b
store i1 %sel, i1 addrspace(1)* %out, align 4
ret void
}

73
llvm/test/CodeGen/AMDGPU/sminmax.ll
View File

@ -128,3 +128,76 @@ define void @v_abs_v4i32(<4 x i32> addrspace(1)* %out, <4 x i32> addrspace(1)* %
store <4 x i32> %res2, <4 x i32> addrspace(1)* %out, align 4
ret void
}
; FUNC-LABEL: {{^}}s_min_max_i32:
; GCN: s_load_dword [[VAL0:s[0-9]+]]
; GCN: s_load_dword [[VAL1:s[0-9]+]]
; GCN-DAG: s_min_i32 s{{[0-9]+}}, [[VAL0]], [[VAL1]]
; GCN-DAG: s_max_i32 s{{[0-9]+}}, [[VAL0]], [[VAL1]]
define void @s_min_max_i32(i32 addrspace(1)* %out0, i32 addrspace(1)* %out1, i32 %val0, i32 %val1) nounwind {
%cond0 = icmp sgt i32 %val0, %val1
%sel0 = select i1 %cond0, i32 %val0, i32 %val1
%sel1 = select i1 %cond0, i32 %val1, i32 %val0
store volatile i32 %sel0, i32 addrspace(1)* %out0, align 4
store volatile i32 %sel1, i32 addrspace(1)* %out1, align 4
ret void
}
; FUNC-LABEL: {{^}}v_min_max_i32:
; GCN: buffer_load_dword [[VAL0:v[0-9]+]]
; GCN: buffer_load_dword [[VAL1:v[0-9]+]]
; GCN-DAG: v_min_i32_e32 v{{[0-9]+}}, [[VAL1]], [[VAL0]]
; GCN-DAG: v_max_i32_e32 v{{[0-9]+}}, [[VAL1]], [[VAL0]]
define void @v_min_max_i32(i32 addrspace(1)* %out0, i32 addrspace(1)* %out1, i32 addrspace(1)* %ptr0, i32 addrspace(1)* %ptr1) nounwind {
%val0 = load volatile i32, i32 addrspace(1)* %ptr0
%val1 = load volatile i32, i32 addrspace(1)* %ptr1
%cond0 = icmp sgt i32 %val0, %val1
%sel0 = select i1 %cond0, i32 %val0, i32 %val1
%sel1 = select i1 %cond0, i32 %val1, i32 %val0
store volatile i32 %sel0, i32 addrspace(1)* %out0, align 4
store volatile i32 %sel1, i32 addrspace(1)* %out1, align 4
ret void
}
; FUNC-LABEL: {{^}}s_min_max_v4i32:
; GCN-DAG: s_min_i32
; GCN-DAG: s_min_i32
; GCN-DAG: s_min_i32
; GCN-DAG: s_min_i32
; GCN-DAG: s_max_i32
; GCN-DAG: s_max_i32
; GCN-DAG: s_max_i32
; GCN-DAG: s_max_i32
define void @s_min_max_v4i32(<4 x i32> addrspace(1)* %out0, <4 x i32> addrspace(1)* %out1, <4 x i32> %val0, <4 x i32> %val1) nounwind {
%cond0 = icmp sgt <4 x i32> %val0, %val1
%sel0 = select <4 x i1> %cond0, <4 x i32> %val0, <4 x i32> %val1
%sel1 = select <4 x i1> %cond0, <4 x i32> %val1, <4 x i32> %val0
store volatile <4 x i32> %sel0, <4 x i32> addrspace(1)* %out0, align 4
store volatile <4 x i32> %sel1, <4 x i32> addrspace(1)* %out1, align 4
ret void
}
; FUNC-LABEL: {{^}}v_min_max_i32_user:
; GCN: v_cmp_gt_i32_e32
; GCN-DAG: v_cndmask_b32_e32
; GCN-DAG: v_cndmask_b32_e32
; GCN-DAG: v_cndmask_b32_e64 v{{[0-9]+}}, 0, 1, vcc
define void @v_min_max_i32_user(i32 addrspace(1)* %out0, i32 addrspace(1)* %out1, i32 addrspace(1)* %ptr0, i32 addrspace(1)* %ptr1) nounwind {
%val0 = load volatile i32, i32 addrspace(1)* %ptr0
%val1 = load volatile i32, i32 addrspace(1)* %ptr1
%cond0 = icmp sgt i32 %val0, %val1
%sel0 = select i1 %cond0, i32 %val0, i32 %val1
%sel1 = select i1 %cond0, i32 %val1, i32 %val0
store volatile i32 %sel0, i32 addrspace(1)* %out0, align 4
store volatile i32 %sel1, i32 addrspace(1)* %out1, align 4
store volatile i1 %cond0, i1 addrspace(1)* undef
ret void
}