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[DAG] Fold (sext (sext_inreg x)) -> (sext (trunc x)) if the trunc is free #77616

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Merged
merged 1 commit into from
Jan 11, 2024
Merged

[DAG] Fold (sext (sext_inreg x)) -> (sext (trunc x)) if the trunc is free #77616

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4 changes: 2 additions & 2 deletions llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -13381,9 +13381,9 @@ SDValue DAGCombiner::visitSIGN_EXTEND(SDNode *N) {
if (N0.getOpcode() == ISD::SIGN_EXTEND_INREG) {
SDValue N00 = N0.getOperand(0);
EVT ExtVT = cast<VTSDNode>(N0->getOperand(1))->getVT();
if (N00.getOpcode() == ISD::TRUNCATE &&
if ((N00.getOpcode() == ISD::TRUNCATE || TLI.isTruncateFree(N00, ExtVT)) &&
(!LegalTypes || TLI.isTypeLegal(ExtVT))) {
SDValue T = DAG.getNode(ISD::TRUNCATE, DL, ExtVT, N00.getOperand(0));
SDValue T = DAG.getNode(ISD::TRUNCATE, DL, ExtVT, N00);
return DAG.getNode(ISD::SIGN_EXTEND, DL, VT, T);
}
}
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8 changes: 4 additions & 4 deletions llvm/test/CodeGen/X86/abds.ll
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Expand Up @@ -141,9 +141,9 @@ define i16 @abd_ext_i16_i32(i16 %a, i32 %b) nounwind {
;
; X64-LABEL: abd_ext_i16_i32:
; X64: # %bb.0:
; X64-NEXT: # kill: def $edi killed $edi def $rdi
; X64-NEXT: movswq %di, %rcx
; X64-NEXT: movslq %esi, %rax
; X64-NEXT: movswl %di, %ecx
; X64-NEXT: movslq %ecx, %rcx
; X64-NEXT: subq %rax, %rcx
; X64-NEXT: movq %rcx, %rax
; X64-NEXT: negq %rax
Expand Down Expand Up @@ -232,9 +232,9 @@ define i32 @abd_ext_i32_i16(i32 %a, i16 %b) nounwind {
;
; X64-LABEL: abd_ext_i32_i16:
; X64: # %bb.0:
; X64-NEXT: # kill: def $esi killed $esi def $rsi
; X64-NEXT: movswq %si, %rax
; X64-NEXT: movslq %edi, %rcx
; X64-NEXT: movswl %si, %eax
; X64-NEXT: cltq
; X64-NEXT: subq %rax, %rcx
; X64-NEXT: movq %rcx, %rax
; X64-NEXT: negq %rax
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3 changes: 1 addition & 2 deletions llvm/test/CodeGen/X86/pr14088.ll
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Expand Up @@ -26,8 +26,7 @@ define i32 @f(i1 %foo, ptr %tm_year2, ptr %bar, i16 %zed, i32 %zed2) {
; CHECK-NEXT: imull $100, %ecx, %ecx
; CHECK-NEXT: subl %ecx, %eax
; CHECK-NEXT: movw %ax, (%rsi)
; CHECK-NEXT: cwtl
; CHECK-NEXT: cltq
; CHECK-NEXT: movswq %ax, %rax
; CHECK-NEXT: imulq $1717986919, %rax, %rax # imm = 0x66666667
; CHECK-NEXT: movq %rax, %rcx
; CHECK-NEXT: shrq $63, %rcx
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