[llvm] [X86] Add slow div64/lea3 tuning flags to Nehalem target (PR #91129)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-x86

Author: Simon Pilgrim (RKSimon)

<details>
<summary>Changes</summary>

I'm confident TuningSlowDivide64 should be set, but less so about TuningSlow3OpsLEA - I'm mainly assuming because most other Intel CPUs set it.

These appear to have been missed because later cpus don't inherit from Nehalem tuning much.

Noticed while cleaning up for #<!-- -->90985

---
Full diff: https://github.com/llvm/llvm-project/pull/91129.diff


3 Files Affected:

- (modified) llvm/lib/Target/X86/X86.td (+2) 
- (modified) llvm/test/CodeGen/X86/2008-08-31-EH_RETURN32.ll (+2-1) 
- (modified) llvm/test/CodeGen/X86/bypass-slow-division-64.ll (+1-1) 


``````````diff
diff --git a/llvm/lib/Target/X86/X86.td b/llvm/lib/Target/X86/X86.td
index 78bc043911f2fc..5efcf5a5bc340f 100644
--- a/llvm/lib/Target/X86/X86.td
+++ b/llvm/lib/Target/X86/X86.td
@@ -873,6 +873,8 @@ def ProcessorFeatures {
   // Nehalem
   list<SubtargetFeature> NHMFeatures = X86_64V2Features;
   list<SubtargetFeature> NHMTuning = [TuningMacroFusion,
+                                      TuningSlow3OpsLEA,
+                                      TuningSlowDivide64,
                                       TuningInsertVZEROUPPER,
                                       TuningNoDomainDelayMov];
 
diff --git a/llvm/test/CodeGen/X86/2008-08-31-EH_RETURN32.ll b/llvm/test/CodeGen/X86/2008-08-31-EH_RETURN32.ll
index 6be9281dc92341..34e557393ff7cb 100644
--- a/llvm/test/CodeGen/X86/2008-08-31-EH_RETURN32.ll
+++ b/llvm/test/CodeGen/X86/2008-08-31-EH_RETURN32.ll
@@ -20,7 +20,8 @@ define ptr @test1(i32 %a, ptr %b) nounwind {
 ; CHECK-NEXT:    movl 12(%ebp), %ecx
 ; CHECK-NEXT:    movl 8(%ebp), %eax
 ; CHECK-NEXT:    movl %ecx, 4(%ebp,%eax)
-; CHECK-NEXT:    leal 4(%ebp,%eax), %ecx
+; CHECK-NEXT:    leal (%eax,%ebp), %ecx
+; CHECK-NEXT:    addl $4, %ecx
 ; CHECK-NEXT:    addl $4, %esp
 ; CHECK-NEXT:    popl %eax
 ; CHECK-NEXT:    popl %edx
diff --git a/llvm/test/CodeGen/X86/bypass-slow-division-64.ll b/llvm/test/CodeGen/X86/bypass-slow-division-64.ll
index 4aaeab4f2f130a..66d7082d9b7c55 100644
--- a/llvm/test/CodeGen/X86/bypass-slow-division-64.ll
+++ b/llvm/test/CodeGen/X86/bypass-slow-division-64.ll
@@ -7,7 +7,7 @@
 ; RUN: llc < %s -mtriple=x86_64-- -mcpu=x86-64-v3       | FileCheck %s --check-prefixes=CHECK,SLOW-DIVQ
 ; RUN: llc < %s -mtriple=x86_64-- -mcpu=x86-64-v4       | FileCheck %s --check-prefixes=CHECK,SLOW-DIVQ
 ; Intel
-; RUN: llc < %s -mtriple=x86_64-- -mcpu=nehalem         | FileCheck %s --check-prefixes=CHECK,FAST-DIVQ
+; RUN: llc < %s -mtriple=x86_64-- -mcpu=nehalem         | FileCheck %s --check-prefixes=CHECK,SLOW-DIVQ
 ; RUN: llc < %s -mtriple=x86_64-- -mcpu=sandybridge     | FileCheck %s --check-prefixes=CHECK,SLOW-DIVQ
 ; RUN: llc < %s -mtriple=x86_64-- -mcpu=haswell         | FileCheck %s --check-prefixes=CHECK,SLOW-DIVQ
 ; RUN: llc < %s -mtriple=x86_64-- -mcpu=skylake         | FileCheck %s --check-prefixes=CHECK,SLOW-DIVQ

``````````

</details>


https://github.com/llvm/llvm-project/pull/91129