[PATCH] D21668: [ARM] Fix cost computation for constant hoisting

[Weiming Zhao via llvm-commits]

weimingz created this revision.
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weimingz set the repository for this revision to rL LLVM.
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Bug: https://llvm.org/bugs/show_bug.cgi?id=28282

When data types like struct is casted to types like i96*, current cost estimator will return 4 although the actual  Imm s very small

Repository:
  rL LLVM

http://reviews.llvm.org/D21668

Files:
  lib/Target/ARM/ARMTargetTransformInfo.cpp
  test/Transforms/ConstantHoisting/ARM/bad-cases.ll

Index: test/Transforms/ConstantHoisting/ARM/bad-cases.ll
===================================================================
--- test/Transforms/ConstantHoisting/ARM/bad-cases.ll
+++ test/Transforms/ConstantHoisting/ARM/bad-cases.ll
@@ -90,3 +90,29 @@
 end:
   ret void
 }
+
+%mystruct = type { [12 x i8] }
+
+define i32 @struct_type_test(%mystruct*  %v0, %mystruct* %v1) {
+;CHECK-LABEL: @struct_type_test
+entry:
+;CHECK-NOT: %const = bitcast i96 32 to i96
+  %v2 = bitcast %mystruct* %v1 to i96*
+  %load0 = load i96, i96* %v2, align 4
+  %v3 = bitcast %mystruct* %v0 to i96*
+  %load1 = load i96, i96* %v3, align 4
+;CHECK: lshr0 = lshr i96 %load0, 32
+  %lshr0 = lshr i96 %load0, 32
+  %cast0 = trunc i96 %lshr0 to i32
+;lshr1 = lshr i96 %load1, 32
+  %lshr1 = lshr i96 %load1, 32
+  %cast1 = trunc i96 %lshr1 to i32
+  %cmp = icmp eq i32 %cast0, %cast1
+  br i1 %cmp, label %if.then, label %if.else
+
+if.then:
+  ret i32 1
+
+if.else:
+  ret i32 2;
+}
Index: lib/Target/ARM/ARMTargetTransformInfo.cpp
===================================================================
--- lib/Target/ARM/ARMTargetTransformInfo.cpp
+++ lib/Target/ARM/ARMTargetTransformInfo.cpp
@@ -19,7 +19,7 @@
   assert(Ty->isIntegerTy());
 
  unsigned Bits = Ty->getPrimitiveSizeInBits();
- if (Bits == 0 || Bits > 64)
+ if (Bits == 0 || Imm.getActiveBits() > 64)
    return 4;
 
   int64_t SImmVal = Imm.getSExtValue();


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