[PATCH] D33656: [PowerPC] Correctly specify the cache line size for Power 7, 8 and 9.

[Stefan Pintilie via Phabricator via llvm-commits]

stefanp created this revision.

The cache line size for Power 7, 8 and 9 is 128 bytes. 
Otherwise a default of 64 bytes is assumed.


https://reviews.llvm.org/D33656

Files:
  lib/Target/PowerPC/PPCTargetTransformInfo.cpp
  test/CodeGen/PowerPC/ppc64-get-cache-line-size.ll


Index: test/CodeGen/PowerPC/ppc64-get-cache-line-size.ll
===================================================================
--- /dev/null
+++ test/CodeGen/PowerPC/ppc64-get-cache-line-size.ll
@@ -0,0 +1,53 @@
+; RUN: llc < %s -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr7 -enable-ppc-prefetching=true | FileCheck %s
+; RUN: llc < %s -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr7 -enable-ppc-prefetching=true -ppc-loop-prefetch-cache-line=64 | FileCheck %s -check-prefix=CHECK-DCBT
+; RUN: llc < %s -mtriple=powerpc64le-unknown-linux-gnu -mcpu=pwr8 -enable-ppc-prefetching=true | FileCheck %s
+; RUN: llc < %s -mtriple=powerpc64le-unknown-linux-gnu -mcpu=pwr8 -enable-ppc-prefetching=true -ppc-loop-prefetch-cache-line=64 | FileCheck %s -check-prefix=CHECK-DCBT
+; RUN: llc < %s -mtriple=powerpc64le-unknown-linux-gnu -mcpu=pwr9 -enable-ppc-prefetching=true | FileCheck %s
+; RUN: llc < %s -mtriple=powerpc64le-unknown-linux-gnu -mcpu=pwr9 -enable-ppc-prefetching=true -ppc-loop-prefetch-cache-line=64 | FileCheck %s -check-prefix=CHECK-DCBT
+; RUN: llc < %s -march=ppc64 -mcpu=a2 -enable-ppc-prefetching=true | FileCheck %s -check-prefix=CHECK-DCBT
+
+; Function Attrs: nounwind
+define signext i32 @main() {
+entry:
+  %call = tail call double* bitcast (double* (...)* @magicf to double* ()*)()
+  %call115 = tail call signext i32 bitcast (i32 (...)* @magici to i32 ()*)()
+  %cmp16 = icmp sgt i32 %call115, 0
+  br i1 %cmp16, label %for.body, label %for.cond.cleanup
+
+for.cond.cleanup.loopexit:                        ; preds = %for.body
+  %phitmp = fptosi double %add5 to i32
+  br label %for.cond.cleanup
+
+for.cond.cleanup:                                 ; preds = %for.cond.cleanup.loopexit, %entry
+  %res.0.lcssa = phi i32 [ 0, %entry ], [ %phitmp, %for.cond.cleanup.loopexit ]
+  ret i32 %res.0.lcssa
+
+for.body:                                         ; preds = %entry, %for.body
+  %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %entry ]
+  %res.017 = phi double [ %add5, %for.body ], [ 0.000000e+00, %entry ]
+  %arrayidx = getelementptr inbounds double, double* %call, i64 %indvars.iv
+  %0 = load double, double* %arrayidx, align 8
+  %add = fadd double %res.017, %0
+  %1 = add nuw nsw i64 %indvars.iv, 8
+  %arrayidx4 = getelementptr inbounds double, double* %call, i64 %1
+  %2 = load double, double* %arrayidx4, align 8
+  %add5 = fadd double %add, %2
+  %indvars.iv.next = add nuw i64 %indvars.iv, 1
+  %call1 = tail call signext i32 bitcast (i32 (...)* @magici to i32 ()*)()
+  %3 = sext i32 %call1 to i64
+  %cmp = icmp slt i64 %indvars.iv.next, %3
+  br i1 %cmp, label %for.body, label %for.cond.cleanup.loopexit
+; CHECK: main
+; CHECK: dcbt
+; CHECK-NOT: dcbt
+; CHECK: blr
+; CHECK-DCBT: main
+; CHECK-DCBT: dcbt
+; CHECK-DCBT: dcbt
+; CHECK-DCBT: blr
+}
+
+declare double* @magicf(...)
+
+declare signext i32 @magici(...)
+
Index: lib/Target/PowerPC/PPCTargetTransformInfo.cpp
===================================================================
--- lib/Target/PowerPC/PPCTargetTransformInfo.cpp
+++ lib/Target/PowerPC/PPCTargetTransformInfo.cpp
@@ -239,9 +239,18 @@
 }
 
 unsigned PPCTTIImpl::getCacheLineSize() {
-  // This is currently only used for the data prefetch pass which is only
-  // enabled for BG/Q by default.
-  return CacheLineSize;
+  // Check first if the user specified a custom line size.
+  if (CacheLineSize.getNumOccurrences() > 0)
+    return CacheLineSize;
+
+  // On P7, P8 or P9 we have a cache line size of 128.
+  unsigned Directive = ST->getDarwinDirective();
+  if (Directive == PPC::DIR_PWR7 || Directive == PPC::DIR_PWR8 ||
+      Directive == PPC::DIR_PWR9)
+    return 128;
+
+  // On other processors return a default of 64 bytes.
+  return 64;
 }
 
 unsigned PPCTTIImpl::getPrefetchDistance() {


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