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R600/SI: Only fold immediates that have one use

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Folding the same immediate into multiple instruction will increase
program size, which can hurt performance.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225405 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Tom Stellard 2015-01-07 22:18:27 +00:00
parent d17010f84d
commit a3ee583339
2 changed files with 43 additions and 1 deletions
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9
lib/Target/R600/SIFoldOperands.cpp
View File

@ -138,6 +138,14 @@ bool SIFoldOperands::runOnMachineFunction(MachineFunction &MF) {
continue;
MachineOperand &OpToFold = MI.getOperand(1);
bool FoldingImm = OpToFold.isImm() || OpToFold.isFPImm();
// Folding immediates with more than one use will increase program side.
// FIXME: This will also reduce register usage, which may be better
// in some cases. A better heuristic is needed.
if (FoldingImm && !TII->isInlineConstant(OpToFold) &&
!MRI.hasOneUse(MI.getOperand(0).getReg()))
continue;
// FIXME: Fold operands with subregs.
if (OpToFold.isReg() &&
@ -158,7 +166,6 @@ bool SIFoldOperands::runOnMachineFunction(MachineFunction &MF) {
continue;
}
bool FoldingImm = OpToFold.isImm() || OpToFold.isFPImm();
APInt Imm;
if (FoldingImm) {

35
test/CodeGen/R600/operand-folding.ll
View File

@ -53,5 +53,40 @@ entry:
ret void
}
; Inline constants should always be folded.
; CHECK-LABEL: {{^}}vector_inline:
; CHECK: v_xor_b32_e32 v{{[0-9]+}}, 5, v{{[0-9]+}}
; CHECK: v_xor_b32_e32 v{{[0-9]+}}, 5, v{{[0-9]+}}
; CHECK: v_xor_b32_e32 v{{[0-9]+}}, 5, v{{[0-9]+}}
; CHECK: v_xor_b32_e32 v{{[0-9]+}}, 5, v{{[0-9]+}}
define void @vector_inline(<4 x i32> addrspace(1)* %out) {
entry:
%tmp0 = call i32 @llvm.r600.read.tidig.x()
%tmp1 = add i32 %tmp0, 1
%tmp2 = add i32 %tmp0, 2
%tmp3 = add i32 %tmp0, 3
%vec0 = insertelement <4 x i32> undef, i32 %tmp0, i32 0
%vec1 = insertelement <4 x i32> %vec0, i32 %tmp1, i32 1
%vec2 = insertelement <4 x i32> %vec1, i32 %tmp2, i32 2
%vec3 = insertelement <4 x i32> %vec2, i32 %tmp3, i32 3
%tmp4 = xor <4 x i32> <i32 5, i32 5, i32 5, i32 5>, %vec3
store <4 x i32> %tmp4, <4 x i32> addrspace(1)* %out
ret void
}
; Immediates with one use should be folded
; CHECK-LABEL: {{^}}imm_one_use:
; CHECK: v_xor_b32_e32 v{{[0-9]+}}, 0x64, v{{[0-9]+}}
define void @imm_one_use(i32 addrspace(1)* %out) {
entry:
%tmp0 = call i32 @llvm.r600.read.tidig.x()
%tmp1 = xor i32 %tmp0, 100
store i32 %tmp1, i32 addrspace(1)* %out
ret void
}
declare i32 @llvm.r600.read.tidig.x() #0
attributes #0 = { readnone }