[X86] Implement TargetLowering::getScalingFactorCost hook.

Scaling factors are not free on X86 because every "complex" addressing mode
breaks the related instruction into 2 allocations instead of 1.

<rdar://problem/16730541>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207301 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 41 insertions, 4 deletions

diff --git a/test/CodeGen/X86/avoid_complex_am.ll b/test/CodeGen/X86/avoid_complex_am.ll
new file mode 100644
index 0000000000..0b7a13d3c0
--- /dev/null
+++ b/test/CodeGen/X86/avoid_complex_am.ll
@@ -0,0 +1,37 @@
+; RUN: opt -S -loop-reduce < %s | FileCheck %s
+; Complex addressing mode are costly.
+; Make loop-reduce prefer unscaled accesses.
+; <rdar://problem/16730541>
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx"
+
+define void @mulDouble(double* nocapture %a, double* nocapture %b, double* nocapture %c) {
+; CHECK: @mulDouble
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+; CHECK: [[IV:%[^ ]+]] = phi i64 [ [[IVNEXT:%[^,]+]], %for.body ], [ 0, %entry ]
+; Only one induction variable should have been generated.
+; CHECK-NOT: phi
+  %indvars.iv = phi i64 [ 1, %entry ], [ %indvars.iv.next, %for.body ]
+  %tmp = add nsw i64 %indvars.iv, -1
+  %arrayidx = getelementptr inbounds double* %b, i64 %tmp
+  %tmp1 = load double* %arrayidx, align 8
+; The induction variable should carry the scaling factor: 1 * 8 = 8.
+; CHECK: [[IVNEXT]] = add nuw nsw i64 [[IV]], 8
+  %indvars.iv.next = add i64 %indvars.iv, 1
+  %arrayidx2 = getelementptr inbounds double* %c, i64 %indvars.iv.next
+  %tmp2 = load double* %arrayidx2, align 8
+  %mul = fmul double %tmp1, %tmp2
+  %arrayidx4 = getelementptr inbounds double* %a, i64 %indvars.iv
+  store double %mul, double* %arrayidx4, align 8
+  %lftr.wideiv = trunc i64 %indvars.iv.next to i32
+; Comparison should be 19 * 8 = 152.
+; CHECK: icmp eq i32 {{%[^,]+}}, 152
+  %exitcond = icmp eq i32 %lftr.wideiv, 20
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body
+  ret void
+}
diff --git a/test/CodeGen/X86/masked-iv-safe.ll b/test/CodeGen/X86/masked-iv-safe.ll
index 4a4d178f6e..7f61e10f5f 100644
--- a/test/CodeGen/X86/masked-iv-safe.ll
+++ b/test/CodeGen/X86/masked-iv-safe.ll
@@ -5,7 +5,7 @@
 
 ; CHECK-LABEL: count_up
 ; CHECK-NOT: {{and|movz|sar|shl}}
-; CHECK: inc
+; CHECK: addq $8,
 ; CHECK-NOT: {{and|movz|sar|shl}}
 ; CHECK: jne
 define void @count_up(double* %d, i64 %n) nounwind {
@@ -71,7 +71,7 @@ return:
 
 ; CHECK-LABEL: count_up_signed
 ; CHECK-NOT: {{and|movz|sar|shl}}
-; CHECK: inc
+; CHECK: addq $8,
 ; CHECK-NOT: {{and|movz|sar|shl}}
 ; CHECK: jne
 define void @count_up_signed(double* %d, i64 %n) nounwind {
@@ -174,7 +174,7 @@ return:
 
 ; CHECK-LABEL: another_count_down
 ; CHECK-NOT: {{and|movz|sar|shl}}
-; CHECK: decq
+; CHECK: addq $-8,
 ; CHECK-NOT: {{and|movz|sar|shl}}
 ; CHECK: jne
 define void @another_count_down(double* %d, i64 %n) nounwind {
@@ -242,7 +242,7 @@ return:
 
 ; CHECK-LABEL: another_count_down_signed
 ; CHECK-NOT: {{and|movz|sar|shl}}
-; CHECK: decq
+; CHECK: addq $-8,
 ; CHECK-NOT: {{and|movz|sar|shl}}
 ; CHECK: jne
 define void @another_count_down_signed(double* %d, i64 %n) nounwind {