[llvm] 11455e4 - [DAG] Unroll vectorized FPOW instructions before widening that will scalarize to libcalls anyway

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2022-05-24T15:44:53+01:00
New Revision: 11455e47588940bd397e72e0c50811001c09295e

URL: https://github.com/llvm/llvm-project/commit/11455e47588940bd397e72e0c50811001c09295e
DIFF: https://github.com/llvm/llvm-project/commit/11455e47588940bd397e72e0c50811001c09295e.diff

LOG: [DAG] Unroll vectorized FPOW instructions before widening that will scalarize to libcalls anyway

Followup to D125988 - FPOW is similar to FREM and will most likely scalarize to libcalls, so unroll before widening to prevent use making additional libcalls with UNDEF args.

Added: 
    

Modified: 
    llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
    llvm/test/CodeGen/X86/pow-libcall.ll

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
index 835d5644cfb4f..ffb36ee155ece 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -3694,6 +3694,7 @@ void DAGTypeLegalizer::WidenVectorResult(SDNode *N, unsigned ResNo) {
     Res = WidenVecRes_Binary(N);
     break;
 
+  case ISD::FPOW:
   case ISD::FREM:
     if (unrollExpandedOp())
       break;
@@ -3704,7 +3705,6 @@ void DAGTypeLegalizer::WidenVectorResult(SDNode *N, unsigned ResNo) {
 
   case ISD::FADD:
   case ISD::FMUL:
-  case ISD::FPOW:
   case ISD::FSUB:
   case ISD::FDIV:
   case ISD::SDIV:

diff  --git a/llvm/test/CodeGen/X86/pow-libcall.ll b/llvm/test/CodeGen/X86/pow-libcall.ll
index e90155e5978cf..492418fffbbad 100644
--- a/llvm/test/CodeGen/X86/pow-libcall.ll
+++ b/llvm/test/CodeGen/X86/pow-libcall.ll
@@ -1,45 +1,30 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: llc -mtriple=x86_64-linux-gnu < %s  | FileCheck %s
 
-; FIXME: Ensure vectorized FPOWs are not widened/unrolled such that they get lowered
+; Ensure vectorized FPOWs are not widened/unrolled such that they get lowered
 ; into libcalls on undef elements.
 
 define float @test_fpow_v2f32_multiuse(<2 x float> %a0, <2 x float> %a1, <2 x float> *%p3) nounwind {
 ; CHECK-LABEL: test_fpow_v2f32_multiuse:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    pushq %rbx
-; CHECK-NEXT:    subq $64, %rsp
+; CHECK-NEXT:    subq $48, %rsp
 ; CHECK-NEXT:    movq %rdi, %rbx
 ; CHECK-NEXT:    movaps %xmm1, {{[-0-9]+}}(%r{{[sb]}}p) # 16-byte Spill
-; CHECK-NEXT:    movaps %xmm0, {{[-0-9]+}}(%r{{[sb]}}p) # 16-byte Spill
-; CHECK-NEXT:    shufps {{.*#+}} xmm0 = xmm0[3,3,3,3]
-; CHECK-NEXT:    shufps {{.*#+}} xmm1 = xmm1[3,3,3,3]
-; CHECK-NEXT:    callq powf at PLT
 ; CHECK-NEXT:    movaps %xmm0, (%rsp) # 16-byte Spill
-; CHECK-NEXT:    movaps {{[-0-9]+}}(%r{{[sb]}}p), %xmm0 # 16-byte Reload
-; CHECK-NEXT:    movhlps {{.*#+}} xmm0 = xmm0[1,1]
-; CHECK-NEXT:    movaps {{[-0-9]+}}(%r{{[sb]}}p), %xmm1 # 16-byte Reload
-; CHECK-NEXT:    movhlps {{.*#+}} xmm1 = xmm1[1,1]
-; CHECK-NEXT:    callq powf at PLT
-; CHECK-NEXT:    unpcklps (%rsp), %xmm0 # 16-byte Folded Reload
-; CHECK-NEXT:    # xmm0 = xmm0[0],mem[0],xmm0[1],mem[1]
-; CHECK-NEXT:    movaps %xmm0, (%rsp) # 16-byte Spill
-; CHECK-NEXT:    movaps {{[-0-9]+}}(%r{{[sb]}}p), %xmm0 # 16-byte Reload
-; CHECK-NEXT:    movaps {{[-0-9]+}}(%r{{[sb]}}p), %xmm1 # 16-byte Reload
 ; CHECK-NEXT:    callq powf at PLT
 ; CHECK-NEXT:    movaps %xmm0, {{[-0-9]+}}(%r{{[sb]}}p) # 16-byte Spill
-; CHECK-NEXT:    movaps {{[-0-9]+}}(%r{{[sb]}}p), %xmm0 # 16-byte Reload
+; CHECK-NEXT:    movaps (%rsp), %xmm0 # 16-byte Reload
 ; CHECK-NEXT:    shufps {{.*#+}} xmm0 = xmm0[1,1,1,1]
 ; CHECK-NEXT:    movaps {{[-0-9]+}}(%r{{[sb]}}p), %xmm1 # 16-byte Reload
 ; CHECK-NEXT:    shufps {{.*#+}} xmm1 = xmm1[1,1,1,1]
 ; CHECK-NEXT:    callq powf at PLT
-; CHECK-NEXT:    movaps {{[-0-9]+}}(%r{{[sb]}}p), %xmm1 # 16-byte Reload
+; CHECK-NEXT:    movaps {{[-0-9]+}}(%r{{[sb]}}p), %xmm2 # 16-byte Reload
+; CHECK-NEXT:    movaps %xmm2, %xmm1
 ; CHECK-NEXT:    unpcklps {{.*#+}} xmm1 = xmm1[0],xmm0[0],xmm1[1],xmm0[1]
-; CHECK-NEXT:    unpcklpd (%rsp), %xmm1 # 16-byte Folded Reload
-; CHECK-NEXT:    # xmm1 = xmm1[0],mem[0]
-; CHECK-NEXT:    addss %xmm1, %xmm0
+; CHECK-NEXT:    addss %xmm2, %xmm0
 ; CHECK-NEXT:    movlps %xmm1, (%rbx)
-; CHECK-NEXT:    addq $64, %rsp
+; CHECK-NEXT:    addq $48, %rsp
 ; CHECK-NEXT:    popq %rbx
 ; CHECK-NEXT:    retq
   %fp = call <2 x float> @llvm.pow.v2f32(<2 x float> %a0, <2 x float> %a1)