arm: Fix fma & fmaf implementations

The vfma.f32|64 z, x, y instruction performs the operation z += x * y without intermediate rounding. The register used for z is both read and written by the instruction. The inline assembly must therefore use the "+" constraint modifier.
RTEMS · Jul 1, 2024 · 920b72f · 920b72f
1 parent c4fb5da
commit 920b72f
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diff --git a/newlib/libm/machine/arm/s_fma_arm.c b/newlib/libm/machine/arm/s_fma_arm.c
@@ -41,7 +41,7 @@
 double
 fma (double x, double y, double z)
 {
-  asm ("vfma.f64 %P0, %P1, %P2" : "=w" (z) : "w" (x), "w" (y));
+  asm ("vfma.f64 %P0, %P1, %P2" : "+w" (z) : "w" (x), "w" (y));
   return z;
 }
 

diff --git a/newlib/libm/machine/arm/sf_fma_arm.c b/newlib/libm/machine/arm/sf_fma_arm.c
@@ -41,7 +41,7 @@
 float
 fmaf (float x, float y, float z)
 {
-  asm ("vfma.f32 %0, %1, %2" : "=t" (z) : "t" (x), "t" (y));
+  asm ("vfma.f32 %0, %1, %2" : "+t" (z) : "t" (x), "t" (y));
   return z;
 }