d74212987b
The fold for merging a GEP of GEP into a single GEP currently bails
if doing so would result in notional overindexing. The justification
given in the comment above this check is dangerously incorrect: GEPs
with notional overindexing are perfectly fine, and if some code
treats them incorrectly, then that code is broken, not the GEP.
Such a GEP might legally appear in source IR, so only preventing
its creation cannot be sufficient. (The constant folder also ends
up canonicalizing the GEP to remove the notional overindexing, but
that's neither here nor there.)
This check dates back to
bd4fef4a89,
and as far as I can tell the original issue this was trying to
patch around has since been resolved.
Differential Revision: https://reviews.llvm.org/D116587
20 lines
1.2 KiB
C++
20 lines
1.2 KiB
C++
// RUN: %clang_cc1 -triple x86_64-linux-gnu -std=c++20 %s -emit-llvm -o - | FileCheck %s --check-prefixes=ITANIUM,CHECK
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// RUN: %clang_cc1 -triple x86_64-windows -std=c++20 %s -emit-llvm -o - | FileCheck %s --check-prefixes=MSABI,CHECK
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struct S { char buf[32]; };
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template<S s> constexpr const char *begin() { return s.buf; }
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template<S s> constexpr const char *end() { return s.buf + __builtin_strlen(s.buf); }
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// ITANIUM: [[HELLO:@_ZTAXtl1StlA32_cLc104ELc101ELc108ELc108ELc111ELc32ELc119ELc111ELc114ELc108ELc100EEEE]]
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// MSABI: [[HELLO:@"[?][?]__N2US@@3D0GI@@0GF@@0GM@@0GM@@0GP@@0CA@@0HH@@0GP@@0HC@@0GM@@0GE@@0A@@0A@@0A@@0A@@0A@@0A@@0A@@0A@@0A@@0A@@0A@@0A@@0A@@0A@@0A@@0A@@0A@@0A@@0A@@0A@@0A@@@@@"]]
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// CHECK-SAME: = linkonce_odr constant { <{ [11 x i8], [21 x i8] }> } { <{ [11 x i8], [21 x i8] }> <{ [11 x i8] c"hello world", [21 x i8] zeroinitializer }> }, comdat
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// ITANIUM: @p
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// MSABI: @"?p@@3PEBDEB"
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// CHECK-SAME: global i8* getelementptr inbounds ({{.*}}* [[HELLO]], i32 0, i32 0, i32 0, i32 0)
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const char *p = begin<S{"hello world"}>();
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// ITANIUM: @q
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// MSABI: @"?q@@3PEBDEB"
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// CHECK-SAME: global i8* getelementptr ({{.*}}* [[HELLO]], i32 0, i32 0, i32 0, i64 11)
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const char *q = end<S{"hello world"}>();
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