[PATCH] D54742: [CodeMetrics] Don't let extends of i1 be free.

[Jonas Paulsson via Phabricator via llvm-commits]

jonpa updated this revision to Diff 180470.
jonpa added a comment.

Test updated per review so that the costs of extensions of i1 are tested directly.

> Sure it does. Run the -cost-model analysis with -cost-kind=code-size and it will call getUserCost().

Ah, thanks and apologies- I was not aware of the -cost-kind=code-size flag.

> I also gave an example that does this in my suggestion.

Yes, indeed, sorry.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D54742/new/

https://reviews.llvm.org/D54742

Files:
  include/llvm/Analysis/TargetTransformInfoImpl.h
  test/Analysis/CostModel/SystemZ/ext-i1-cost.ll


Index: test/Analysis/CostModel/SystemZ/ext-i1-cost.ll
===================================================================
--- /dev/null
+++ test/Analysis/CostModel/SystemZ/ext-i1-cost.ll
@@ -0,0 +1,45 @@
+; RUN: opt < %s -cost-model -cost-kind=code-size -analyze \
+; RUN:   -mtriple=s390x-unknown-linux -mcpu=z13  | FileCheck %s
+;
+; Check that getUserCost() does not return TCC_Free for extensions of
+; i1.
+
+define i64 @fun1(i64 %v) {
+; CHECK-LABEL: 'fun1'
+; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   %cmp = icmp eq i64 %v, 0
+; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   %z = zext i1 %cmp to i64
+; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   ret i64 %z
+  %cmp = icmp eq i64 %v, 0
+  %z = zext i1 %cmp to i64
+  ret i64 %z
+}
+
+define i64 @fun2(i64 %v) {
+; CHECK-LABEL: 'fun2'
+; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   %cmp = icmp eq i64 %v, 0
+; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   %z = sext i1 %cmp to i64
+; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   ret i64 %z
+  %cmp = icmp eq i64 %v, 0
+  %z = sext i1 %cmp to i64
+  ret i64 %z
+}
+
+define double @fun3(i64 %v) {
+; CHECK-LABEL: 'fun3'
+; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   %cmp = icmp eq i64 %v, 0
+; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   %z = uitofp i1 %cmp to double
+; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   ret double %z
+  %cmp = icmp eq i64 %v, 0
+  %z = uitofp i1 %cmp to double
+  ret double %z
+}
+
+define double @fun4(i64 %v) {
+; CHECK-LABEL: 'fun4'
+; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   %cmp = icmp eq i64 %v, 0
+; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   %z = sitofp i1 %cmp to double
+; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   ret double %z
+  %cmp = icmp eq i64 %v, 0
+  %z = sitofp i1 %cmp to double
+  ret double %z
+}
Index: include/llvm/Analysis/TargetTransformInfoImpl.h
===================================================================
--- include/llvm/Analysis/TargetTransformInfoImpl.h
+++ include/llvm/Analysis/TargetTransformInfoImpl.h
@@ -807,15 +807,12 @@
       return static_cast<T *>(this)->getCallCost(F, Arguments);
     }
 
-    if (const CastInst *CI = dyn_cast<CastInst>(U)) {
-      // Result of a cmp instruction is often extended (to be used by other
-      // cmp instructions, logical or return instructions). These are usually
-      // nop on most sane targets.
-      if (isa<CmpInst>(CI->getOperand(0)))
-        return TTI::TCC_Free;
-      if (isa<SExtInst>(CI) || isa<ZExtInst>(CI) || isa<FPExtInst>(CI))
-        return static_cast<T *>(this)->getExtCost(CI, Operands.back());
-    }
+    if (isa<SExtInst>(U) || isa<ZExtInst>(U) || isa<FPExtInst>(U))
+      // The old behaviour of generally treating extensions of i1 to be free
+      // has been removed. A target that needs it should override this
+      // method.
+      return static_cast<T *>(this)->getExtCost(cast<Instruction>(U),
+                                                Operands.back());
 
     return static_cast<T *>(this)->getOperationCost(
         Operator::getOpcode(U), U->getType(),


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