[PATCH] D21668: [ARM] Fix cost computation for constant hoisting
Weiming Zhao via llvm-commits
llvm-commits at lists.llvm.org
Sun Jun 26 23:09:49 PDT 2016
weimingz set the repository for this revision to rL LLVM.
weimingz updated this revision to Diff 61931.
weimingz added a comment.
Hi Renato,
Thanks for the feedback.
I Simplified the test case and added comments.
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 +90,20 @@
end:
ret void
}
+
+;PR 28282: even when data type is larger than 64-bit, the bit width of the
+;constant operand could be smaller than 64-bit. In this case, there is no
+;benefit to hoist the constant.
+define i32 @struct_type_test(i96 %a0, i96 %a1) {
+;CHECK-LABEL: @struct_type_test
+entry:
+;CHECK-NOT: %const = bitcast i96 32 to i96
+;CHECK: lshr0 = lshr i96 %a0, 32
+ %lshr0 = lshr i96 %a0, 32
+ %cast0 = trunc i96 %lshr0 to i32
+;CHECK: lshr1 = lshr i96 %a1, 32
+ %lshr1 = lshr i96 %a1, 32
+ %cast1 = trunc i96 %lshr1 to i32
+ %ret = add i32 %cast0, %cast1
+ ret i32 %ret
+}
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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