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[ConstProp] Handle insertelement constants 

Previously ConstantFoldExtractElementInstruction() would only work with
insertelement instructions, not contants. This properly handles
insertelement constants as well.

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D85865
This commit is contained in:
Arthur Eubanks 2020-08-10 12:53:30 -07:00
parent ae6523cd62
commit 41f49736a9
2 changed files with 25 additions and 0 deletions
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9
llvm/lib/IR/ConstantFold.cpp
View File

@ -853,6 +853,15 @@ Constant *llvm::ConstantFoldExtractElementInstruction(Constant *Val,
}
return CE->getWithOperands(Ops, ValVTy->getElementType(), false,
Ops[0]->getType()->getPointerElementType());
} else if (CE->getOpcode() == Instruction::InsertElement) {
if (const auto *IEIdx = dyn_cast<ConstantInt>(CE->getOperand(2))) {
if (APSInt::isSameValue(APSInt(IEIdx->getValue()),
APSInt(CIdx->getValue()))) {
return CE->getOperand(1);
} else {
return ConstantExpr::getExtractElement(CE->getOperand(0), CIdx);
}
}
}
}

16
llvm/test/Transforms/InstSimplify/vscale.ll
View File

@ -95,6 +95,22 @@ define i32 @insert_extract_element_same_vec_idx_2() {
ret i32 %r
}
define i32 @insert_extract_element_same_vec_idx_3() {
; CHECK-LABEL: @insert_extract_element_same_vec_idx_3(
; CHECK-NEXT: ret i32 1
;
%r = extractelement <vscale x 4 x i32> insertelement (<vscale x 4 x i32> undef, i32 1, i64 4), i64 4
ret i32 %r
}
define i32 @insert_extract_element_same_vec_idx_4() {
; CHECK-LABEL: @insert_extract_element_same_vec_idx_4(
; CHECK-NEXT: ret i32 1
;
%r = extractelement <vscale x 4 x i32> insertelement (<vscale x 4 x i32> insertelement (<vscale x 4 x i32> undef, i32 1, i32 4), i32 2, i64 3), i64 4
ret i32 %r
}
; more complicated expressions
define <vscale x 2 x i1> @cmp_le_smax_always_true(<vscale x 2 x i64> %x) {