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From: "vincenzo.innocente at cern dot ch" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/49513] New: introducing a product inhibit vectorization Date: Thu, 23 Jun 2011 06:55:00 -0000 [thread overview] Message-ID: <bug-49513-4@http.gcc.gnu.org/bugzilla/> (raw) http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49513 Summary: introducing a product inhibit vectorization Product: gcc Version: 4.7.0 Status: UNCONFIRMED Severity: major Priority: P3 Component: tree-optimization AssignedTo: unassigned@gcc.gnu.org ReportedBy: vincenzo.innocente@cern.ch in the simple example below the first loop vectorize, the second not I'm using gcc version 4.7.0 20110528 (experimental) (GCC) #include<cmath> float __attribute__ ((aligned(16))) a[1024]; float __attribute__ ((aligned(16))) s[1024]; float __attribute__ ((aligned(16))) c[1024]; inline float bar(float y, float x ){ float xx = fabs(x); float yy = fabs(y); float tmp =0.0f; if (yy>xx) { tmp = yy; yy=xx; xx=tmp; } float t=yy/xx; return t; } void foo1() { for (int i=0; i!=1024; ++i) { float z = i; a[i] = bar(s[i],c[i]); } } void foo2() { for (int i=0; i!=1024; ++i) { float z = i; a[i] = bar(z*s[i],z*c[i]); } } c++ -std=c++0x -Ofast -c vectBug.cc -ftree-vectorizer-verbose=7 vectBug.cc:21: note: vect_model_load_cost: aligned. vectBug.cc:21: note: vect_get_data_access_cost: inside_cost = 1, outside_cost = 0. vectBug.cc:21: note: vect_model_load_cost: aligned. vectBug.cc:21: note: vect_get_data_access_cost: inside_cost = 2, outside_cost = 0. vectBug.cc:21: note: vect_model_store_cost: aligned. vectBug.cc:21: note: vect_get_data_access_cost: inside_cost = 3, outside_cost = 0. vectBug.cc:21: note: vect_model_load_cost: aligned. vectBug.cc:21: note: vect_model_load_cost: inside_cost = 1, outside_cost = 0 . vectBug.cc:21: note: vect_model_load_cost: aligned. vectBug.cc:21: note: vect_model_load_cost: inside_cost = 1, outside_cost = 0 . vectBug.cc:21: note: vect_model_simple_cost: inside_cost = 1, outside_cost = 0 . vectBug.cc:21: note: vect_model_simple_cost: inside_cost = 1, outside_cost = 0 . vectBug.cc:21: note: vect_model_simple_cost: inside_cost = 1, outside_cost = 0 . vectBug.cc:21: note: vect_model_store_cost: aligned. vectBug.cc:21: note: vect_model_store_cost: inside_cost = 1, outside_cost = 0 . vectBug.cc:21: note: Cost model analysis: Vector inside of loop cost: 6 Vector outside of loop cost: 0 Scalar iteration cost: 8 Scalar outside cost: 0 prologue iterations: 0 epilogue iterations: 0 Calculated minimum iters for profitability: 1 vectBug.cc:21: note: Profitability threshold = 3 vectBug.cc:21: note: LOOP VECTORIZED. vectBug.cc:20: note: vectorized 1 loops in function. vectBug.cc:27: note: not vectorized: control flow in loop. vectBug.cc:26: note: vectorized 0 loops in function.
next reply other threads:[~2011-06-23 6:55 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2011-06-23 6:55 vincenzo.innocente at cern dot ch [this message] 2011-06-23 11:55 ` [Bug tree-optimization/49513] PRE inhibits if-conversion and vectorization rguenth at gcc dot gnu.org 2011-06-23 12:17 ` vincenzo.innocente at cern dot ch 2011-06-23 12:59 ` [Bug tree-optimization/49513] DOM " rguenth at gcc dot gnu.org 2011-07-08 21:12 ` law at redhat dot com 2023-05-02 0:46 ` pinskia at gcc dot gnu.org
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