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by the SRoA "promote to large integer" code, eliminating some type conversions like this: %94 = zext i16 %93 to i32 ; <i32> [#uses=2] %96 = lshr i32 %94, 8 ; <i32> [#uses=1] %101 = trunc i32 %96 to i8 ; <i8> [#uses=1] This also unblocks other xforms from happening, now clang is able to compile: struct S { float A, B, C, D; }; float foo(struct S A) { return A.A + A.B+A.C+A.D; } into: _foo: ## @foo ## BB#0: ## %entry pshufd $1, %xmm0, %xmm2 addss %xmm0, %xmm2 movdqa %xmm1, %xmm3 addss %xmm2, %xmm3 pshufd $1, %xmm1, %xmm0 addss %xmm3, %xmm0 ret on x86-64, instead of: _foo: ## @foo ## BB#0: ## %entry movd %xmm0, %rax shrq $32, %rax movd %eax, %xmm2 addss %xmm0, %xmm2 movapd %xmm1, %xmm3 addss %xmm2, %xmm3 movd %xmm1, %rax shrq $32, %rax movd %eax, %xmm0 addss %xmm3, %xmm0 ret This seems pretty close to optimal to me, at least without using horizontal adds. This also triggers in lots of other code, including SPEC. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112278 91177308-0d34-0410-b5e6-96231b3b80d8 |
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Hello | ||
InstCombine | ||
Instrumentation | ||
IPO | ||
Scalar | ||
Utils | ||
Makefile |