diff options
| -rw-r--r-- | lib/Target/X86/README-SSE.txt | 26 | ||||
| -rw-r--r-- | lib/Target/X86/README.txt | 27 | ||||
| -rw-r--r-- | test/CodeGen/X86/coalescer-commute2.ll | 34 |
3 files changed, 34 insertions, 53 deletions
diff --git a/lib/Target/X86/README-SSE.txt b/lib/Target/X86/README-SSE.txt index 2ccabca2fc..acfe411623 100644 --- a/lib/Target/X86/README-SSE.txt +++ b/lib/Target/X86/README-SSE.txt @@ -131,32 +131,6 @@ feasible. //===---------------------------------------------------------------------===// -Teach the coalescer to commute 2-addr instructions, allowing us to eliminate -the reg-reg copy in this example: - -float foo(int *x, float *y, unsigned c) { - float res = 0.0; - unsigned i; - for (i = 0; i < c; i++) { - float xx = (float)x[i]; - xx = xx * y[i]; - xx += res; - res = xx; - } - return res; -} - -LBB_foo_3: # no_exit - cvtsi2ss %XMM0, DWORD PTR [%EDX + 4*%ESI] - mulss %XMM0, DWORD PTR [%EAX + 4*%ESI] - addss %XMM0, %XMM1 - inc %ESI - cmp %ESI, %ECX -**** movaps %XMM1, %XMM0 - jb LBB_foo_3 # no_exit - -//===---------------------------------------------------------------------===// - Codegen: if (copysign(1.0, x) == copysign(1.0, y)) into: diff --git a/lib/Target/X86/README.txt b/lib/Target/X86/README.txt index fccddc79f4..65de926a3e 100644 --- a/lib/Target/X86/README.txt +++ b/lib/Target/X86/README.txt @@ -933,33 +933,6 @@ _test: //===---------------------------------------------------------------------===// -This is a "commutable two-address" register coallescing deficiency: - -define <4 x float> @test1(<4 x float> %V) { -entry: - %tmp8 = shufflevector <4 x float> %V, <4 x float> undef, - <4 x i32> < i32 3, i32 2, i32 1, i32 0 > - %add = add <4 x float> %tmp8, %V - ret <4 x float> %add -} - -this codegens to: - -_test1: - pshufd $27, %xmm0, %xmm1 - addps %xmm0, %xmm1 - movaps %xmm1, %xmm0 - ret - -instead of: - -_test1: - pshufd $27, %xmm0, %xmm1 - addps %xmm1, %xmm0 - ret - -//===---------------------------------------------------------------------===// - Leaf functions that require one 4-byte spill slot have a prolog like this: _foo: diff --git a/test/CodeGen/X86/coalescer-commute2.ll b/test/CodeGen/X86/coalescer-commute2.ll new file mode 100644 index 0000000000..ce4abf1d31 --- /dev/null +++ b/test/CodeGen/X86/coalescer-commute2.ll @@ -0,0 +1,34 @@ +; RUN: llvm-as < %s | llc -march=x86-64 | grep paddw | count 2 +; RUN: llvm-as < %s | llc -march=x86-64 | not grep mov + +; The 2-addr pass should ensure that identical code is produced for these functions +; no extra copy should be generated. + +define <2 x i64> @test1(<2 x i64> %x, <2 x i64> %y) nounwind { +entry: + %tmp6 = bitcast <2 x i64> %y to <8 x i16> ; <<8 x i16>> [#uses=1] + %tmp8 = bitcast <2 x i64> %x to <8 x i16> ; <<8 x i16>> [#uses=1] + %tmp9 = add <8 x i16> %tmp8, %tmp6 ; <<8 x i16>> [#uses=1] + %tmp10 = bitcast <8 x i16> %tmp9 to <2 x i64> ; <<2 x i64>> [#uses=1] + ret <2 x i64> %tmp10 +} + +define <2 x i64> @test2(<2 x i64> %x, <2 x i64> %y) nounwind { +entry: + %tmp6 = bitcast <2 x i64> %x to <8 x i16> ; <<8 x i16>> [#uses=1] + %tmp8 = bitcast <2 x i64> %y to <8 x i16> ; <<8 x i16>> [#uses=1] + %tmp9 = add <8 x i16> %tmp8, %tmp6 ; <<8 x i16>> [#uses=1] + %tmp10 = bitcast <8 x i16> %tmp9 to <2 x i64> ; <<2 x i64>> [#uses=1] + ret <2 x i64> %tmp10 +} + + +; The coalescer should commute the add to avoid a copy. +define <4 x float> @test3(<4 x float> %V) { +entry: + %tmp8 = shufflevector <4 x float> %V, <4 x float> undef, + <4 x i32> < i32 3, i32 2, i32 1, i32 0 > + %add = add <4 x float> %tmp8, %V + ret <4 x float> %add +} + |