[llvm] [DAGCombiner] Combine frem into fdiv+ftrunc+fma (PR #67642)
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Thu Sep 28 01:13:42 PDT 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-selectiondag
<details>
<summary>Changes</summary>
Migrated from https://reviews.llvm.org/D108284
---
Full diff: https://github.com/llvm/llvm-project/pull/67642.diff
2 Files Affected:
- (modified) llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (+12)
- (modified) llvm/test/CodeGen/PowerPC/frem.ll (+37-105)
``````````diff
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 0d34ebb117667aa..2f5f295e199188a 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -16958,6 +16958,18 @@ SDValue DAGCombiner::visitFREM(SDNode *N) {
if (SDValue NewSel = foldBinOpIntoSelect(N))
return NewSel;
+ // (frem x, y) -> (fma (fneg (ftrunc (fdiv x, y))), y, x)
+ if (Flags.hasApproximateFuncs() && Flags.hasNoSignedZeros() &&
+ Flags.hasNoInfs() && !TLI.isOperationLegalOrCustom(ISD::FREM, VT) &&
+ TLI.isOperationLegalOrCustom(ISD::FTRUNC, VT) &&
+ TLI.isOperationLegalOrCustom(ISD::FMA, VT)) {
+ SDLoc Loc(N);
+ SDValue Div = DAG.getNode(ISD::FDIV, Loc, VT, N0, N1);
+ SDValue Trunc = DAG.getNode(ISD::FTRUNC, Loc, VT, Div);
+ return DAG.getNode(ISD::FMA, Loc, VT,
+ DAG.getNode(ISD::FNEG, Loc, VT, Trunc), N1, N0);
+ }
+
return SDValue();
}
diff --git a/llvm/test/CodeGen/PowerPC/frem.ll b/llvm/test/CodeGen/PowerPC/frem.ll
index 8cb68e60f7f9b71..dff9c796289e96e 100644
--- a/llvm/test/CodeGen/PowerPC/frem.ll
+++ b/llvm/test/CodeGen/PowerPC/frem.ll
@@ -4,16 +4,13 @@
define float @frem32(float %a, float %b) {
; CHECK-LABEL: frem32:
; CHECK: # %bb.0: # %entry
-; CHECK-NEXT: mflr 0
-; CHECK-NEXT: stdu 1, -32(1)
-; CHECK-NEXT: std 0, 48(1)
-; CHECK-NEXT: .cfi_def_cfa_offset 32
-; CHECK-NEXT: .cfi_offset lr, 16
-; CHECK-NEXT: bl fmodf
-; CHECK-NEXT: nop
-; CHECK-NEXT: addi 1, 1, 32
-; CHECK-NEXT: ld 0, 16(1)
-; CHECK-NEXT: mtlr 0
+; CHECK-NEXT: xsresp 0, 2
+; CHECK-NEXT: fmr 4, 1
+; CHECK-NEXT: xsmulsp 3, 1, 0
+; CHECK-NEXT: xsnmsubasp 4, 2, 3
+; CHECK-NEXT: xsmaddasp 3, 0, 4
+; CHECK-NEXT: xsrdpiz 0, 3
+; CHECK-NEXT: xsnmsubasp 1, 0, 2
; CHECK-NEXT: blr
entry:
%rem = frem fast float %a, %b
@@ -23,16 +20,17 @@ entry:
define double @frem64(double %a, double %b) {
; CHECK-LABEL: frem64:
; CHECK: # %bb.0: # %entry
-; CHECK-NEXT: mflr 0
-; CHECK-NEXT: stdu 1, -32(1)
-; CHECK-NEXT: std 0, 48(1)
-; CHECK-NEXT: .cfi_def_cfa_offset 32
-; CHECK-NEXT: .cfi_offset lr, 16
-; CHECK-NEXT: bl fmod
-; CHECK-NEXT: nop
-; CHECK-NEXT: addi 1, 1, 32
-; CHECK-NEXT: ld 0, 16(1)
-; CHECK-NEXT: mtlr 0
+; CHECK-NEXT: vspltisw 2, -1
+; CHECK-NEXT: xsredp 0, 2
+; CHECK-NEXT: fmr 4, 1
+; CHECK-NEXT: xvcvsxwdp 3, 34
+; CHECK-NEXT: xsmaddadp 3, 2, 0
+; CHECK-NEXT: xsnmsubadp 0, 0, 3
+; CHECK-NEXT: xsmuldp 3, 1, 0
+; CHECK-NEXT: xsnmsubadp 4, 2, 3
+; CHECK-NEXT: xsmaddadp 3, 0, 4
+; CHECK-NEXT: xsrdpiz 0, 3
+; CHECK-NEXT: xsnmsubadp 1, 0, 2
; CHECK-NEXT: blr
entry:
%rem = frem fast double %a, %b
@@ -42,59 +40,13 @@ entry:
define <4 x float> @frem4x32(<4 x float> %a, <4 x float> %b) {
; CHECK-LABEL: frem4x32:
; CHECK: # %bb.0: # %entry
-; CHECK-NEXT: mflr 0
-; CHECK-NEXT: stdu 1, -96(1)
-; CHECK-NEXT: std 0, 112(1)
-; CHECK-NEXT: .cfi_def_cfa_offset 96
-; CHECK-NEXT: .cfi_offset lr, 16
-; CHECK-NEXT: .cfi_offset v28, -64
-; CHECK-NEXT: .cfi_offset v29, -48
-; CHECK-NEXT: .cfi_offset v30, -32
-; CHECK-NEXT: .cfi_offset v31, -16
-; CHECK-NEXT: xxsldwi 0, 34, 34, 3
-; CHECK-NEXT: stxv 60, 32(1) # 16-byte Folded Spill
-; CHECK-NEXT: xscvspdpn 1, 0
-; CHECK-NEXT: xxsldwi 0, 35, 35, 3
-; CHECK-NEXT: stxv 61, 48(1) # 16-byte Folded Spill
-; CHECK-NEXT: stxv 62, 64(1) # 16-byte Folded Spill
-; CHECK-NEXT: stxv 63, 80(1) # 16-byte Folded Spill
-; CHECK-NEXT: xscvspdpn 2, 0
-; CHECK-NEXT: vmr 31, 3
-; CHECK-NEXT: vmr 30, 2
-; CHECK-NEXT: bl fmodf
-; CHECK-NEXT: nop
-; CHECK-NEXT: xxsldwi 0, 62, 62, 1
-; CHECK-NEXT: xscpsgndp 61, 1, 1
-; CHECK-NEXT: xscvspdpn 1, 0
-; CHECK-NEXT: xxsldwi 0, 63, 63, 1
-; CHECK-NEXT: xscvspdpn 2, 0
-; CHECK-NEXT: bl fmodf
-; CHECK-NEXT: nop
-; CHECK-NEXT: # kill: def $f1 killed $f1 def $vsl1
-; CHECK-NEXT: xxmrghd 0, 1, 61
-; CHECK-NEXT: xscvspdpn 1, 62
-; CHECK-NEXT: xscvspdpn 2, 63
-; CHECK-NEXT: xvcvdpsp 60, 0
-; CHECK-NEXT: bl fmodf
-; CHECK-NEXT: nop
-; CHECK-NEXT: xxswapd 0, 62
-; CHECK-NEXT: xscpsgndp 61, 1, 1
-; CHECK-NEXT: xscvspdpn 1, 0
-; CHECK-NEXT: xxswapd 0, 63
-; CHECK-NEXT: xscvspdpn 2, 0
-; CHECK-NEXT: bl fmodf
-; CHECK-NEXT: nop
-; CHECK-NEXT: # kill: def $f1 killed $f1 def $vsl1
-; CHECK-NEXT: xxmrghd 0, 61, 1
-; CHECK-NEXT: lxv 63, 80(1) # 16-byte Folded Reload
-; CHECK-NEXT: lxv 62, 64(1) # 16-byte Folded Reload
-; CHECK-NEXT: lxv 61, 48(1) # 16-byte Folded Reload
-; CHECK-NEXT: xvcvdpsp 34, 0
-; CHECK-NEXT: vmrgew 2, 2, 28
-; CHECK-NEXT: lxv 60, 32(1) # 16-byte Folded Reload
-; CHECK-NEXT: addi 1, 1, 96
-; CHECK-NEXT: ld 0, 16(1)
-; CHECK-NEXT: mtlr 0
+; CHECK-NEXT: xvresp 0, 35
+; CHECK-NEXT: vmr 4, 2
+; CHECK-NEXT: xvmulsp 1, 34, 0
+; CHECK-NEXT: xvnmsubasp 36, 35, 1
+; CHECK-NEXT: xvmaddasp 1, 0, 36
+; CHECK-NEXT: xvrspiz 0, 1
+; CHECK-NEXT: xvnmsubasp 34, 0, 35
; CHECK-NEXT: blr
entry:
%rem = frem fast <4 x float> %a, %b
@@ -104,38 +56,18 @@ entry:
define <2 x double> @frem2x64(<2 x double> %a, <2 x double> %b) {
; CHECK-LABEL: frem2x64:
; CHECK: # %bb.0: # %entry
-; CHECK-NEXT: mflr 0
-; CHECK-NEXT: stdu 1, -80(1)
-; CHECK-NEXT: std 0, 96(1)
-; CHECK-NEXT: .cfi_def_cfa_offset 80
-; CHECK-NEXT: .cfi_offset lr, 16
-; CHECK-NEXT: .cfi_offset v29, -48
-; CHECK-NEXT: .cfi_offset v30, -32
-; CHECK-NEXT: .cfi_offset v31, -16
-; CHECK-NEXT: stxv 62, 48(1) # 16-byte Folded Spill
-; CHECK-NEXT: stxv 63, 64(1) # 16-byte Folded Spill
-; CHECK-NEXT: vmr 31, 3
-; CHECK-NEXT: xscpsgndp 2, 63, 63
-; CHECK-NEXT: vmr 30, 2
-; CHECK-NEXT: xscpsgndp 1, 62, 62
-; CHECK-NEXT: stxv 61, 32(1) # 16-byte Folded Spill
-; CHECK-NEXT: bl fmod
-; CHECK-NEXT: nop
-; CHECK-NEXT: xscpsgndp 61, 1, 1
-; CHECK-NEXT: xxswapd 1, 62
-; CHECK-NEXT: xxswapd 2, 63
-; CHECK-NEXT: # kill: def $f1 killed $f1 killed $vsl1
-; CHECK-NEXT: # kill: def $f2 killed $f2 killed $vsl2
-; CHECK-NEXT: bl fmod
-; CHECK-NEXT: nop
-; CHECK-NEXT: # kill: def $f1 killed $f1 def $vsl1
-; CHECK-NEXT: xxmrghd 34, 61, 1
-; CHECK-NEXT: lxv 63, 64(1) # 16-byte Folded Reload
-; CHECK-NEXT: lxv 62, 48(1) # 16-byte Folded Reload
-; CHECK-NEXT: lxv 61, 32(1) # 16-byte Folded Reload
-; CHECK-NEXT: addi 1, 1, 80
-; CHECK-NEXT: ld 0, 16(1)
-; CHECK-NEXT: mtlr 0
+; CHECK-NEXT: addis 3, 2, .LCPI3_0 at toc@ha
+; CHECK-NEXT: xvredp 0, 35
+; CHECK-NEXT: vmr 4, 2
+; CHECK-NEXT: addi 3, 3, .LCPI3_0 at toc@l
+; CHECK-NEXT: lxv 1, 0(3)
+; CHECK-NEXT: xvmaddadp 1, 35, 0
+; CHECK-NEXT: xvnmsubadp 0, 0, 1
+; CHECK-NEXT: xvmuldp 1, 34, 0
+; CHECK-NEXT: xvnmsubadp 36, 35, 1
+; CHECK-NEXT: xvmaddadp 1, 0, 36
+; CHECK-NEXT: xvrdpiz 0, 1
+; CHECK-NEXT: xvnmsubadp 34, 0, 35
; CHECK-NEXT: blr
entry:
%rem = frem fast <2 x double> %a, %b
``````````
</details>
https://github.com/llvm/llvm-project/pull/67642
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