[SelectionDAGBuilder][X86] Don't form FMAXNUM for f16 vectors if FMAXNUM needs to be promoted. #114943
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…NUM needs to be promoted. In llvm#70357, I changed a isLegalOrCustom to isLegalOrCustomOrPromote in visitSelect to enable integer min/max to be formed when the operation was promoted. Unfortunately, this also affected floating point. For floating point, fmaxnum may require a libcall so we also need to check if the operation on the promoted type is legal or custom. Other changes to RISC-V have seen made the original change untested so this patch restores the original isLegalOrCustom.
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@llvm/pr-subscribers-backend-x86 @llvm/pr-subscribers-llvm-selectiondag Author: Craig Topper (topperc) ChangesIn #70357, I changed a isLegalOrCustom to isLegalOrCustomOrPromote in visitSelect to enable integer min/max to be formed when the operation was promoted. Unfortunately, this also affected floating point. For floating point, fmaxnum may require a libcall so we also need to check if the operation on the promoted type is legal or custom. Other changes to RISC-V have seen made the original change untested so this patch restores the original isLegalOrCustom. Fixes #114520. Full diff: https://github.com/llvm/llvm-project/pull/114943.diff 2 Files Affected:
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 199d02afb97e3a..f8122b77b46def 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -3775,7 +3775,7 @@ void SelectionDAGBuilder::visitSelect(const User &I) {
}
if (!IsUnaryAbs && Opc != ISD::DELETED_NODE &&
- (TLI.isOperationLegalOrCustomOrPromote(Opc, VT) ||
+ (TLI.isOperationLegalOrCustom(Opc, VT) ||
(UseScalarMinMax &&
TLI.isOperationLegalOrCustom(Opc, VT.getScalarType()))) &&
// If the underlying comparison instruction is used by any other
diff --git a/llvm/test/CodeGen/X86/pr114520.ll b/llvm/test/CodeGen/X86/pr114520.ll
new file mode 100644
index 00000000000000..f9dd3fce8c1ec0
--- /dev/null
+++ b/llvm/test/CodeGen/X86/pr114520.ll
@@ -0,0 +1,19 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc < %s -mtriple=x86_64-none-unknown-elf -mattr=+avx512vl | FileCheck %s
+
+define half @r_2_10001(half %0) {
+; CHECK-LABEL: r_2_10001:
+; CHECK: # %bb.0: # %entry
+; CHECK-NEXT: vpextrw $0, %xmm0, %eax
+; CHECK-NEXT: vmovd %eax, %xmm0
+; CHECK-NEXT: vcvtph2ps %xmm0, %xmm0
+; CHECK-NEXT: vucomiss {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
+; CHECK-NEXT: movl $64512, %ecx # imm = 0xFC00
+; CHECK-NEXT: cmoval %eax, %ecx
+; CHECK-NEXT: vpinsrw $0, %ecx, %xmm0, %xmm0
+; CHECK-NEXT: retq
+entry:
+ %cmp2 = fcmp ogt half %0, 0xHFC00
+ %cond.v = select i1 %cmp2, half %0, half 0xHFC00
+ ret half %cond.v
+}
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arsenm
reviewed
Nov 5, 2024
arsenm
approved these changes
Nov 5, 2024
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In #70357, I changed a isLegalOrCustom to isLegalOrCustomOrPromote in visitSelect to enable integer min/max to be formed when the operation was promoted. Unfortunately, this also affected floating point. For floating point, fmaxnum may require a libcall so we also need to check if the operation on the promoted type is legal or custom.
Other changes to RISC-V have seen made the original change untested so this patch restores the original isLegalOrCustom.
Fixes #114520.