[llvm] r312534 - [X86] Limit store merge size when implicitfloat is enabled (PR34421)

[Simon Pilgrim via llvm-commits]

Author: rksimon
Date: Tue Sep  5 06:40:29 2017
New Revision: 312534

URL: http://llvm.org/viewvc/llvm-project?rev=312534&view=rev
Log:
[X86] Limit store merge size when implicitfloat is enabled (PR34421)

As suggested by @niravd : https://bugs.llvm.org/show_bug.cgi?id=34421#c2

Differential Revision: https://reviews.llvm.org/D37464

Added:
    llvm/trunk/test/CodeGen/X86/pr34421.ll
Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
    llvm/trunk/lib/Target/X86/X86ISelLowering.h

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=312534&r1=312533&r2=312534&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Tue Sep  5 06:40:29 2017
@@ -4611,6 +4611,20 @@ bool X86TargetLowering::isCheapToSpecula
   return Subtarget.hasLZCNT();
 }
 
+bool X86TargetLowering::canMergeStoresTo(unsigned AddressSpace, EVT MemVT,
+                                         const SelectionDAG &DAG) const {
+  // Do not merge to float value size (128 bytes) if no implicit
+  // float attribute is set.
+  bool NoFloat = DAG.getMachineFunction().getFunction()->hasFnAttribute(
+      Attribute::NoImplicitFloat);
+
+  if (NoFloat) {
+    unsigned MaxIntSize = Subtarget.is64Bit() ? 64 : 32;
+    return (MemVT.getSizeInBits() <= MaxIntSize);
+  }
+  return true;
+}
+
 bool X86TargetLowering::isCtlzFast() const {
   return Subtarget.hasFastLZCNT();
 }

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.h?rev=312534&r1=312533&r2=312534&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.h (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.h Tue Sep  5 06:40:29 2017
@@ -814,6 +814,9 @@ namespace llvm {
 
     bool mergeStoresAfterLegalization() const override { return true; }
 
+    bool canMergeStoresTo(unsigned AddressSpace, EVT MemVT,
+                          const SelectionDAG &DAG) const override;
+
     bool isCheapToSpeculateCttz() const override;
 
     bool isCheapToSpeculateCtlz() const override;

Added: llvm/trunk/test/CodeGen/X86/pr34421.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/pr34421.ll?rev=312534&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/pr34421.ll (added)
+++ llvm/trunk/test/CodeGen/X86/pr34421.ll Tue Sep  5 06:40:29 2017
@@ -0,0 +1,40 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=i686-apple-macosx10.13.0 | FileCheck %s --check-prefix=X86
+; RUN: llc < %s -mtriple=x86_64-apple-macosx10.13.0 | FileCheck %s --check-prefix=X64
+
+define void @thread_selfcounts() noimplicitfloat noredzone nounwind {
+; X86-LABEL: thread_selfcounts:
+; X86:       ## BB#0: ## %entry
+; X86-NEXT:    subl $44, %esp
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %ecx
+; X86-NEXT:    movl %ecx, {{[0-9]+}}(%esp)
+; X86-NEXT:    movl %eax, (%esp)
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %ecx
+; X86-NEXT:    movl %ecx, {{[0-9]+}}(%esp)
+; X86-NEXT:    movl %eax, {{[0-9]+}}(%esp)
+; X86-NEXT:    ## -- End function
+;
+; X64-LABEL: thread_selfcounts:
+; X64:       ## BB#0: ## %entry
+; X64-NEXT:    subq $40, %rsp
+; X64-NEXT:    movq {{[0-9]+}}(%rsp), %rax
+; X64-NEXT:    movq {{[0-9]+}}(%rsp), %rcx
+; X64-NEXT:    movq %rax, (%rsp)
+; X64-NEXT:    movq %rcx, {{[0-9]+}}(%rsp)
+; X64-NEXT:    ## -- End function
+entry:
+  %counts = alloca [2 x i64], align 16
+  %thread_counts = alloca [3 x i64], align 16
+  %arraydecay = getelementptr inbounds [3 x i64], [3 x i64]* %thread_counts, i64 0, i64 0
+  %0 = load i64, i64* %arraydecay, align 16
+  %arrayidx3 = getelementptr inbounds [2 x i64], [2 x i64]* %counts, i64 0, i64 0
+  store i64 %0, i64* %arrayidx3, align 16
+  %arrayidx6 = getelementptr inbounds [3 x i64], [3 x i64]* %thread_counts, i64 0, i64 1
+  %1 = load i64, i64* %arrayidx6, align 8
+  %arrayidx10 = getelementptr inbounds [2 x i64], [2 x i64]* %counts, i64 0, i64 1
+  store i64 %1, i64* %arrayidx10, align 8
+  unreachable
+}
+